Vulnerability-Lookup

CVE-2026-54697 (GCVE-0-2026-54697)

Vulnerability from cvelistv5 – Published: 2026-10-13 15:54 – Updated: 2026-10-13 16:07

Title

ConnectBot SSH: Excessive allocation and integer overflow in DER private-key parsing

Summary

ConnectBot SSH Client Library is written in Kotlin with Kaitai Struct and KStateMachine. Prior to 0.3.1, DerReader.readLength() accepts excessive long-form DER length octets, accumulates them into an Int, and primitive readers allocate arrays without checking the declared size against the remaining input. An application or user that loads an attacker-provided private-key file through SshClient.authenticatePublicKey(), SshKeys.decodePemPrivateKey(), SshSigning.sign(), or SshSigning.getPublicKey() can trigger integer wraparound, excessive allocation, or an uncaught OutOfMemoryError. SSH server host keys and agent-forwarding messages do not use this application-supplied private-key input path. No usable weakened key and no confidentiality or integrity impact have been demonstrated. This issue is fixed in version 0.3.1.

Severity

6.7 (Medium)


                        
                          CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-10-13 16:07 UTC

CWE

CWE-190 - Integer Overflow or Wraparound
CWE-789 - Memory Allocation with Excessive Size Value

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 7771 records in the last 180 days details

References

3 references

URL	Tags
https://github.com/connectbot/cbssh/security/advi…	x_refsource_CONFIRM
https://github.com/connectbot/cbssh/commit/2bb917…	x_refsource_MISC
https://github.com/connectbot/cbssh/releases/tag/v0.3.1	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
connectbot	cbssh	Affected: < 0.3.1	guessed

Show details on NVD website

JSON

To clipboard

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}

FKIE_CVE-2026-54697

Vulnerability from fkie_nvd - Published: 2026-10-13 16:17 - Updated: 2026-10-16 20:04

Severity

6.7 (Medium) - CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/connectbot/cbssh/commit/2bb917517bec0df229a02ca768d6eae84be72df0
	security-advisories@github.com	https://github.com/connectbot/cbssh/releases/tag/v0.3.1
	security-advisories@github.com	https://github.com/connectbot/cbssh/security/advisories/GHSA-vc8p-8pxg-rfwg

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "cbssh",
          "vendor": "connectbot",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 0.3.1"
            }
          ]
        }
      ],
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    }
  ],
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    {
      "lang": "en",
      "value": "ConnectBot SSH Client Library is written in Kotlin with Kaitai Struct and KStateMachine. Prior to 0.3.1, DerReader.readLength() accepts excessive long-form DER length octets, accumulates them into an Int, and primitive readers allocate arrays without checking the declared size against the remaining input. An application or user that loads an attacker-provided private-key file through SshClient.authenticatePublicKey(), SshKeys.decodePemPrivateKey(), SshSigning.sign(), or SshSigning.getPublicKey() can trigger integer wraparound, excessive allocation, or an uncaught OutOfMemoryError. SSH server host keys and agent-forwarding messages do not use this application-supplied private-key input path. No usable weakened key and no confidentiality or integrity impact have been demonstrated. This issue is fixed in version 0.3.1."
    }
  ],
  "id": "CVE-2026-54697",
  "lastModified": "2026-10-16T20:04:29.760",
  "metrics": {
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        "cvssData": {
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          "attackVector": "LOCAL",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 6.7,
          "baseSeverity": "MEDIUM",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
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          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
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}

GHSA-VC8P-8PXG-RFWG

Vulnerability from github – Published: 2026-06-12 21:02 – Updated: 2026-07-08 17:35

Summary

ConnectBot SSH Client Library: Excessive allocation and integer overflow in DER private-key parsing

Details

Summary

The DER parser used for application-supplied private keys did not safely validate encoded length values before converting them to Int values or allocating arrays.

A malformed private-key file could encode a length that overflowed or wrapped around, or request an allocation much larger than the available input. This could cause parsing errors or an uncaught OutOfMemoryError, potentially terminating the application process.

Details

The issue was in DerReader.readLength() and primitive readers such as readInteger().

readLength() previously accepted up to 127 length octets and accumulated them into an Int:

length = (length shl 8) or nextByte

This permitted integer overflow. For example:

0x1_0000_0001 wrapped to 1.
0x8000_0000 wrapped to Int.MIN_VALUE.

Primitive readers then allocated memory based on the resulting value without first checking it against the remaining input:

val bytes = ByteArray(length)
data.get(bytes)

A six-byte DER value declaring a 1 GiB INTEGER caused an immediate OutOfMemoryError when tested with a constrained JVM heap. Because OutOfMemoryError is not an Exception, it is not caught by the public-key authentication error handling and may terminate the application process.

A zero-length DER INTEGER is also invalid, but it does not produce BigInteger.ZERO: Java throws NumberFormatException when constructing a BigInteger from an empty byte array. No weakened or usable cryptographic key has been demonstrated through this issue.

Attack Requirements

The affected DER parser processes private-key material explicitly supplied by the application through APIs such as:

SshClient.authenticatePublicKey()
SshKeys.decodePemPrivateKey()
SshSigning.sign()
SshSigning.getPublicKey()

The DER input is not populated from SSH server host keys or agent-forwarding requests. Exploitation therefore requires a user or application to load an attacker-provided private-key file. The issue is not remotely exploitable by an SSH server.

Impact

Successful exploitation can cause:

Incorrect DER length interpretation due to integer wraparound
Excessive memory allocation
An uncaught OutOfMemoryError
Loss of availability of the affected application process

There is no demonstrated confidentiality or integrity impact.

Remediation

The DER parser now:

Rejects indefinite lengths
Explicitly limits long-form lengths to Int.SIZE_BYTES (four octets) and rejects values above Int.MAX_VALUE
Accumulates long-form lengths in a Long before converting to Int
Rejects truncated and non-minimal length encodings
Checks declared lengths against the remaining input before allocation or advancing the input position
Rejects zero-length DER INTEGER, BIT STRING, and OBJECT IDENTIFIER values where an empty encoding is invalid
Rejects non-canonical DER INTEGER encodings with redundant sign octets

The bounds checks are implemented in shared DER reader helpers and apply to INTEGER, OCTET STRING, BIT STRING, OBJECT IDENTIFIER, SEQUENCE, context-specific values, and skipped values. PKCS#1 RSA and SEC1 EC private keys pass application-supplied DER directly through these helpers. PKCS#8 input is parsed by the JCA provider, and OpenSSH private keys use a separate wire-format parser rather than DerReader.

Severity

6.7 (Medium)


                  
                    CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Maven",
        "name": "org.connectbot.sshlib:sshlib"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "0.3.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-54697"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-190",
      "CWE-789"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-12T21:02:15Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "## Summary\n\nThe DER parser used for application-supplied private keys did not safely validate encoded length values before converting them to `Int` values or allocating arrays.\n\nA malformed private-key file could encode a length that overflowed or wrapped around, or request an allocation much larger than the available input. This could cause parsing errors or an uncaught `OutOfMemoryError`, potentially terminating the application process.\n\n## Details\n\nThe issue was in `DerReader.readLength()` and primitive readers such as `readInteger()`.\n\n`readLength()` previously accepted up to 127 length octets and accumulated them into an `Int`:\n\n```kotlin\nlength = (length shl 8) or nextByte\n```\n\nThis permitted integer overflow. For example:\n\n- `0x1_0000_0001` wrapped to `1`.\n- `0x8000_0000` wrapped to `Int.MIN_VALUE`.\n\nPrimitive readers then allocated memory based on the resulting value without first checking it against the remaining input:\n\n```kotlin\nval bytes = ByteArray(length)\ndata.get(bytes)\n```\n\nA six-byte DER value declaring a 1 GiB INTEGER caused an immediate `OutOfMemoryError` when tested with a constrained JVM heap. Because `OutOfMemoryError` is not an `Exception`, it is not caught by the public-key authentication error handling and may terminate the application process.\n\nA zero-length DER INTEGER is also invalid, but it does not produce `BigInteger.ZERO`: Java throws `NumberFormatException` when constructing a `BigInteger` from an empty byte array. No weakened or usable cryptographic key has been demonstrated through this issue.\n\n## Attack Requirements\n\nThe affected DER parser processes private-key material explicitly supplied by the application through APIs such as:\n\n- `SshClient.authenticatePublicKey()`\n- `SshKeys.decodePemPrivateKey()`\n- `SshSigning.sign()`\n- `SshSigning.getPublicKey()`\n\nThe DER input is not populated from SSH server host keys or agent-forwarding requests. Exploitation therefore requires a user or application to load an attacker-provided private-key file. The issue is not remotely exploitable by an SSH server.\n\n## Impact\n\nSuccessful exploitation can cause:\n\n- Incorrect DER length interpretation due to integer wraparound\n- Excessive memory allocation\n- An uncaught `OutOfMemoryError`\n- Loss of availability of the affected application process\n\nThere is no demonstrated confidentiality or integrity impact.\n\n## Remediation\n\nThe DER parser now:\n\n- Rejects indefinite lengths\n- Explicitly limits long-form lengths to `Int.SIZE_BYTES` (four octets) and rejects values above `Int.MAX_VALUE`\n- Accumulates long-form lengths in a `Long` before converting to `Int`\n- Rejects truncated and non-minimal length encodings\n- Checks declared lengths against the remaining input before allocation or advancing the input position\n- Rejects zero-length DER INTEGER, BIT STRING, and OBJECT IDENTIFIER values where an empty encoding is invalid\n- Rejects non-canonical DER INTEGER encodings with redundant sign octets\n\nThe bounds checks are implemented in shared DER reader helpers and apply to INTEGER, OCTET STRING, BIT STRING, OBJECT IDENTIFIER, SEQUENCE, context-specific values, and skipped values. PKCS#1 RSA and SEC1 EC private keys pass application-supplied DER directly through these helpers. PKCS#8 input is parsed by the JCA provider, and OpenSSH private keys use a separate wire-format parser rather than `DerReader`.",
  "id": "GHSA-vc8p-8pxg-rfwg",
  "modified": "2026-07-08T17:35:52Z",
  "published": "2026-06-12T21:02:15Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/connectbot/cbssh/security/advisories/GHSA-vc8p-8pxg-rfwg"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/connectbot/cbssh"
    },
    {
      "type": "WEB",
      "url": "https://github.com/connectbot/cbssh/releases/tag/v0.3.1"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "ConnectBot SSH Client Library: Excessive allocation and integer overflow in DER private-key parsing"
}

Sightings

Author	Source	Type	Date	Other

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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.

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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CVE-2026-54697 (GCVE-0-2026-54697)

FKIE_CVE-2026-54697

GHSA-VC8P-8PXG-RFWG

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