CVE-2026-91767

MEDIUMPre-NVD 6.56.5—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2% (3rd percentile of EPSS-scored CVEs). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — 3 sources updated this week
6.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 6.5Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

php_openssl_matches_wildcard_name() in ext/openssl/xp_ssl.c underflows the length argument passed to memchr() when a TLS server certificate presents a wildcard name whose literal characters are together longer than the hostname being verified. A malicious server presenting such a certificate makes the PHP client read up to SIZE_MAX bytes past the end of a heap allocation. The path is reachable from any default client stream, because verify_peer_name is enabled by default.

CVSS v3
6.5
EG Score
6.5MEDIUMmedium confidence
EG Risk
29
EG Risk 29/100CISA SSVC

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
Severity65% × 45%
Exploitation0% × 40%
Automatability0% × 15%
CISA SSVC: Track at every mission impact level.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.2%
EPSS %ILE
3rd
KEV
Not listed

CISA SSVCTrack at every mission impact level.

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

September 25, 2026

Last Modified

September 29, 2026

Advisory Details (1)

Auto-updated Sep 25, 2026
🔬 Proof of concept available. Patch available. Sources: github.
github Patch Available🟡 PoC Available

Heap-buffer-overflow in php_openssl_matches_wildcard_name on crafted server cert wildcard CN · Advisory · php/php-src · GitHub

https://github.com/php/php-src/security/advisories/GHSA-xr7j-rvgx-xq5p

Vendor Advisories for CVE-2026-91767(2)

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

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatphp-main-8.5.11-2.hum12026-09-23redhat

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.

Data Freshness Timeline

(refreshed 22× in last 7d / 28× 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.

  1. 2026-10-04 06:45 UTCEG score recompute
  2. 2026-10-04 06:45 UTCVendor advisory
  3. 2026-10-03 04:40 UTCEG score recompute
  4. 2026-10-03 04:40 UTCVendor advisory
  5. 2026-10-02 02:34 UTCEG score recompute
  6. 2026-10-02 02:34 UTCVendor advisory
  7. 2026-10-01 19:51 UTCEPSS rescore
  8. 2026-10-01 00:25 UTCEG score recompute
  9. 2026-10-01 00:25 UTCVendor advisory
  10. 2026-09-30 15:04 UTCEPSS rescore
  11. 2026-09-29 22:16 UTCVendor advisory
  12. 2026-09-29 16:46 UTCEG score recompute
  13. 2026-09-29 16:46 UTCVendor advisory
  14. 2026-09-28 14:26 UTCEG score recompute
  15. 2026-09-28 14:26 UTCVendor advisory
  16. 2026-09-28 13:52 UTCEPSS rescore
  17. 2026-09-28 13:52 UTCEPSS rescore
  18. 2026-09-28 13:44 UTCEG score recompute
  19. 2026-09-28 13:44 UTCVendor advisory
  20. 2026-09-28 01:33 UTCEG score recompute
  21. 2026-09-28 01:33 UTCVendor advisory
  22. 2026-09-27 13:49 UTCEPSS rescore
  23. 2026-09-26 23:28 UTCEG score recompute
  24. 2026-09-26 23:28 UTCVendor advisory
  25. 2026-09-26 15:59 UTCEPSS rescore
Show 3 more
  1. 2026-09-25 21:18 UTCEG score recompute
  2. 2026-09-25 20:54 UTCEG score recompute
  3. 2026-09-25 20:54 UTCMITRE cvelistV5first tracked

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-91767?
CVE-2026-91767 is a medium vulnerability published on September 25, 2026. phpopensslmatcheswildcardname() in ext/openssl/xpssl.c underflows the length argument passed to memchr() when a TLS server certificate presents a wildcard name whose literal characters are together longer than the hostname being verified. A malicious server presenting such a certificate makes the…
When was CVE-2026-91767 disclosed?
CVE-2026-91767 was first published on September 25, 2026, with the most recent update on September 29, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-91767 actively exploited?
CVE-2026-91767 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (3rd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-91767?
CVE-2026-91767 has a CVSS base score of 6.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-91767?
A fix for CVE-2026-91767 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-91767 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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