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
Elevated
8.1
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 4%CVSS: 8.1Exploit: NoneExposed: 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)
EPSS
89.9%
KEV
Not listed

Published

May 22, 2026

Last Modified

July 15, 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(8)

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

Patch Availability(8)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntunginx-light (1.18.0-6ubuntu14.12) @ jammy2026-06-29ubuntu
ubuntunginx-light (1.10.3-0ubuntu0.16.04.5+esm7) @ xenial2026-06-29ubuntu
redhatnginx-2:1.26.3-6.el10_2.42026-06-25redhat
redhatnginx:1.26-9080020260609152155.92026-06-25redhat
redhatnginx:1.24-8100020260611094050.489197e62026-06-24redhat
redhatnginx-2:1.20.1-28.el9_8.32026-06-24redhat
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 7× in last 7d / 58× 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 173 total refreshes for this CVE.

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

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 ↗

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 15, 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 89.9% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
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

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