Vulnerability-Lookup

GHSA-H78R-86C6-JGP4

Vulnerability from github – Published: 2026-05-26 13:30 – Updated: 2026-05-26 13:30

Details

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_rewrite_module module. This vulnerability exists when a rewrite directive uses a regex pattern with distinct, overlapping Perl-Compatible Regular Expression (PCRE) captures (for example, ^/((.*))$) and a replacement string that references multiple such captures (for example, $1$2) in a redirect or arguments context. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Severity

8.1 (High)


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

9.2 (Critical)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-9256"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-122"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-05-22T15:16:27Z",
    "severity": "CRITICAL"
  },
  "details": "NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_rewrite_module module. This vulnerability exists when a rewrite directive uses a regex pattern with distinct, overlapping Perl-Compatible Regular Expression (PCRE) captures (for example, ^/((.*))$) and a replacement string that references multiple such captures (for example, $1$2) in a redirect or arguments context. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR. \n\n\nNote: Software versions which have reached End of Technical Support (EoTS) are not evaluated.",
  "id": "GHSA-h78r-86c6-jgp4",
  "modified": "2026-05-26T13:30:17Z",
  "published": "2026-05-26T13:30:17Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-9256"
    },
    {
      "type": "WEB",
      "url": "https://my.f5.com/manage/s/article/K000161377"
    },
    {
      "type": "WEB",
      "url": "http://www.openwall.com/lists/oss-security/2026/05/22/14"
    }
  ],
  "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"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
      "type": "CVSS_V4"
    }
  ]
}

CVE-2026-9256 (GCVE-0-2026-9256)

Vulnerability from cvelistv5 – Published: 2026-05-22 14:11 – Updated: 2026-05-28 18:20 X_F5

Title

NGINX ngx_http_rewrite_module vulnerability

Summary

Severity

8.1 (High)


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

9.2 (Critical)


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

CWE

CWE-122 - Heap-based Buffer Overflow

Assigner

References

1 reference

URL	Tags
https://my.f5.com/manage/s/article/K000161377	vendor-advisory

Impacted products

2 products

Vendor	Product	Version
F5	NGINX Plus	Affected: 37.0 , < 37.0.1.1 (custom) Affected: R36 , < R36 P5 (custom) Affected: R32 , < R32 P7 (custom)
F5	NGINX Open Source	Affected: 1.31.0 , < 1.31.1 (custom) Affected: 1.30.0 , < 1.30.2 (custom) Affected: 0.1.17 , ≤ 0.9.7 (custom)

Date Public

2026-05-22 14:00

Credits

"F5 acknowledges Mufeed VH of Winfunc Research, Nebula Security (@nebusecurity), and Vexera AI for bringing this issue to our attention and following the highest standards of coordinated disclosure."

Show details on NVD website

JSON

To clipboard

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Sightings

Author	Source	Type	Date	Other

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-H78R-86C6-JGP4

CVE-2026-9256 (GCVE-0-2026-9256)

Tags

Sightings

Nomenclature