CVE-2026-9256

HIGHPre-NVD 8.18.1—
EchelonGraph scoreMEDIUM confidence

Score 8.1 from GitHub Security Advisory (severity: CRITICAL) published 2026-05-26. a secondary CVSS source baseline 8.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — Patch released this weekElevated
8.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 10%CVSS: 8.1Exploit: Elevated riskExposed: 0

A fix is available — apply it.

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.

CVSS v3
8.1
EG Score
8.1(medium)
EG Risk
52(Track)
EG Risk 52/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity81% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
10%
EPSS %ILE
95%
KEV
Not listed

Published

May 22, 2026

Last Modified

July 24, 2026

Advisory Details (1)

Auto-updated May 28, 2026
No patch confirmed yet.
generic

myF5

https://my.f5.com/manage/s/article/K000161377

Vendor Advisories for CVE-2026-9256(9)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(10)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntunginx-light (1.28.3-2ubuntu1.2) @ resolute2026-07-26ubuntu
ubuntunginx-light (1.10.3-0ubuntu0.16.04.5+esm7) @ xenial2026-07-26ubuntu
redhatrhui5/rhua-rhel9:17847950762026-07-23redhat
redhatdiscovery/discovery-ui-rhel9:17827565412026-06-29redhat
redhatnginx:1.26-9080020260609152155.92026-06-25redhat
redhatnginx-2:1.26.3-6.el10_2.42026-06-25redhat
redhatnginx-2:1.20.1-28.el9_8.32026-06-24redhat
redhatnginx:1.24-8100020260611094050.489197e62026-06-24redhat
redhatnginx:1.24-9080020260610161820.92026-06-23redhat
redhatnginx-main-1.30.2-1.hum12026-05-23redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Additional Vendor Advisories

(3)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 12× in last 7d / 40× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 150 total refreshes for this CVE.

  1. 2026-07-26 14:54 UTCEPSS rescore
  2. 2026-07-26 08:07 UTCEG score recompute
  3. 2026-07-26 08:07 UTCVendor advisory
  4. 2026-07-26 08:06 UTCGHSA enrichment
  5. 2026-07-25 14:18 UTCEPSS rescore
  6. 2026-07-24 14:18 UTCEPSS rescore
  7. 2026-07-23 14:18 UTCEPSS rescore
  8. 2026-07-23 03:23 UTCEG score recompute
  9. 2026-07-22 14:08 UTCEPSS rescore
  10. 2026-07-21 15:25 UTCEPSS rescore
  11. 2026-07-21 15:25 UTCEPSS rescore
  12. 2026-07-20 17:08 UTCEPSS rescore
  13. 2026-07-19 14:31 UTCEPSS rescore
  14. 2026-07-19 02:29 UTCEPSS rescore
  15. 2026-07-18 10:04 UTCEPSS rescore
  16. 2026-07-17 18:59 UTCOSV refresh
  17. 2026-07-16 17:03 UTCEPSS rescore
  18. 2026-07-15 16:57 UTCEPSS rescore
  19. 2026-07-15 02:00 UTCEPSS rescore
  20. 2026-07-13 22:31 UTCEPSS rescore
  21. 2026-07-13 06:13 UTCEPSS rescore
  22. 2026-07-12 05:46 UTCEPSS rescore
  23. 2026-07-11 08:27 UTCEPSS rescore
  24. 2026-07-09 19:10 UTCEPSS rescore
  25. 2026-07-08 15:16 UTCEPSS rescore
Show 75 more
  1. 2026-07-07 13:46 UTCEPSS rescore
  2. 2026-07-06 16:27 UTCEPSS rescore
  3. 2026-07-06 02:23 UTCEPSS rescore
  4. 2026-07-05 02:31 UTCEPSS rescore
  5. 2026-07-04 06:31 UTCEPSS rescore
  6. 2026-07-04 06:31 UTCEPSS rescore
  7. 2026-07-01 15:07 UTCEPSS rescore
  8. 2026-06-30 23:22 UTCEPSS rescore
  9. 2026-06-29 16:38 UTCVendor advisory
  10. 2026-06-29 16:38 UTCGHSA enrichment
  11. 2026-06-28 08:11 UTCVendor advisory
  12. 2026-06-28 08:11 UTCGHSA enrichment
  13. 2026-06-28 04:56 UTCEPSS rescore
  14. 2026-06-27 19:52 UTCVendor advisory
  15. 2026-06-27 19:52 UTCGHSA enrichment
  16. 2026-06-27 07:32 UTCVendor advisory
  17. 2026-06-27 07:32 UTCGHSA enrichment
  18. 2026-06-27 03:08 UTCEPSS rescore
  19. 2026-06-26 19:13 UTCVendor advisory
  20. 2026-06-26 19:13 UTCGHSA enrichment
  21. 2026-06-26 03:18 UTCVendor advisory
  22. 2026-06-26 03:18 UTCGHSA enrichment
  23. 2026-06-25 13:56 UTCVendor advisory
  24. 2026-06-25 13:56 UTCGHSA enrichment
  25. 2026-06-25 13:50 UTCEPSS rescore
  26. 2026-06-24 14:05 UTCEPSS rescore
  27. 2026-06-23 21:33 UTCEPSS rescore
  28. 2026-06-22 14:25 UTCEPSS rescore
  29. 2026-06-21 14:56 UTCEPSS rescore
  30. 2026-06-21 01:59 UTCEPSS rescore
  31. 2026-06-19 19:26 UTCEPSS rescore
  32. 2026-06-18 17:52 UTCEPSS rescore
  33. 2026-06-17 23:41 UTCVendor advisory
  34. 2026-06-17 23:41 UTCGHSA enrichment
  35. 2026-06-17 17:53 UTCEPSS rescore
  36. 2026-06-17 10:55 UTCVendor advisory
  37. 2026-06-17 10:55 UTCGHSA enrichment
  38. 2026-06-16 19:22 UTCVendor advisory
  39. 2026-06-16 19:22 UTCGHSA enrichment
  40. 2026-06-16 17:53 UTCEPSS rescore
  41. 2026-06-16 03:15 UTCVendor advisory
  42. 2026-06-16 03:15 UTCGHSA enrichment
  43. 2026-06-15 17:49 UTCEPSS rescore
  44. 2026-06-15 17:49 UTCEPSS rescore
  45. 2026-06-15 14:54 UTCVendor advisory
  46. 2026-06-15 14:54 UTCGHSA enrichment
  47. 2026-06-14 23:18 UTCEPSS rescore
  48. 2026-06-14 23:08 UTCVendor advisory
  49. 2026-06-14 23:08 UTCGHSA enrichment
  50. 2026-06-14 10:49 UTCVendor advisory
  51. 2026-06-14 10:49 UTCGHSA enrichment
  52. 2026-06-13 23:00 UTCEPSS rescore
  53. 2026-06-13 22:31 UTCVendor advisory
  54. 2026-06-13 22:31 UTCGHSA enrichment
  55. 2026-06-13 10:12 UTCVendor advisory
  56. 2026-06-13 10:12 UTCGHSA enrichment
  57. 2026-06-12 23:12 UTCEPSS rescore
  58. 2026-06-12 23:12 UTCEPSS rescore
  59. 2026-06-12 21:51 UTCVendor advisory
  60. 2026-06-12 21:51 UTCGHSA enrichment
  61. 2026-06-12 09:31 UTCVendor advisory
  62. 2026-06-12 09:31 UTCGHSA enrichment
  63. 2026-06-11 21:12 UTCVendor advisory
  64. 2026-06-11 21:12 UTCGHSA enrichment
  65. 2026-06-11 14:00 UTCEPSS rescore
  66. 2026-06-11 08:53 UTCVendor advisory
  67. 2026-06-11 08:53 UTCGHSA enrichment
  68. 2026-06-10 22:19 UTCEPSS rescore
  69. 2026-06-10 20:34 UTCVendor advisory
  70. 2026-06-10 20:34 UTCGHSA enrichment
  71. 2026-06-10 13:22 UTCEPSS rescore
  72. 2026-06-10 08:15 UTCVendor advisory
  73. 2026-06-10 08:15 UTCGHSA enrichment
  74. 2026-06-09 19:56 UTCVendor advisory
  75. 2026-06-09 19:56 UTCGHSA enrichment

Publicly available exploits

(2 references)

Working exploit code is in the public domain (2 GitHub PoCs). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoCy198nt/Nginx-chain-Rift-Poolslip
    First seen Jun 5, 2026

    Nginx RCE chain PoC with CVE-2026-9256 and CVE-2026-42945

    Open source ↗
  • GitHub PoC3nou9h/CVE-2026-9256-Poc
    First seen May 28, 2026
    Open source ↗

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-9256?
CVE-2026-9256 is a high vulnerability published on May 22, 2026. NGINX Plus and NGINX Open Source have a vulnerability in the ngxhttprewrite_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…
When was CVE-2026-9256 disclosed?
CVE-2026-9256 was first published in the National Vulnerability Database on May 22, 2026, with the most recent update on July 24, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-9256 actively exploited?
CVE-2026-9256 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 10% probability of exploitation in the next 30 days, which ranks it in the top 4.9% of all scored CVEs.
What is the CVSS score of CVE-2026-9256?
CVE-2026-9256 has a CVSS v3 base score of 8.1 (NVD).
How do I remediate CVE-2026-9256?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-9256, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-9256

Explore →

Is Your Infrastructure Affected by CVE-2026-9256?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs