VulnerabilityPublished 1 Oct 2026Updated 29 Oct 2026

CVE-2026-91767: php_openssl_matches_wildcard_name · Heap-buffer-overflow

Affects phpSource GCVE Database

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Authoritative record:CVE-2026-91767· Medium 6.5

Not known to be exploited · CVSS 6.5 Medium · fixed in 8.5.11 : update php when convenient.

Data as of 29 Oct 2026, 14:41 UTC

CVSS 3.1 base score

6.5Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.1% chance of exploitation in 30 days – higher than 1% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 8.5.11, 8.4.26, 8.3.35 +1

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

Attack Vector: Adjacent
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Adjacent: The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 25 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade php to 8.5.11, 8.4.26, 8.3.35 or 8.2.34.

Affected software

Product	Affected	Fixed in
Bitnamiphp`pkg:bitnami/php`Other threats	Affected >=8.2.0 <8.2.34 >=8.3.0 <8.3.35 >=8.4.0 <8.4.26 >=8.5.0 <8.5.11	Fixed in 8.2.34 8.3.35 8.4.26 8.5.11

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A patch is available and users should upgrade to PHP versions 8.2.34, 8.3.35, 8.4.26, or 8.5.11 or later to remediate this vulnerability. Since verify_peer_name is enabled by default, no configuration changes are required to mitigate the issue other than applying the official fixes.

Description

A heap-buffer-overflow vulnerability exists in the PHP function php_openssl_matches_wildcard_name() when processing TLS server certificates with wildcard names longer than the hostname being verified. This flaw allows a malicious server to cause the PHP client to read memory beyond the allocated heap buffer. The vulnerability is reachable by default because peer name verification is enabled by default in PHP client streams. It affects multiple PHP versions prior to fixed releases.

Impact

A malicious TLS server can exploit this vulnerability by presenting a specially crafted wildcard certificate with a common name longer than the hostname being verified, causing the PHP client to read memory beyond allocated buffers. This can lead to memory corruption and potentially undefined behavior or crashes in PHP client applications that perform TLS peer name verification. The vulnerability is medium severity and does not have confirmed exploitation in the wild.

Summary

The vulnerability in php_openssl_matches_wildcard_name() in ext/openssl/xp_ssl.c causes an underflow of the length argument passed to memchr() when a TLS server certificate presents a wildcard name whose literal characters exceed the length of the hostname being verified. This leads to a heap-buffer-overflow where the PHP client may read up to SIZE_MAX bytes past the end of a heap allocation. Since verify_peer_name is enabled by default, this code path is reachable from any default client stream. The issue affects PHP versions >=8.2.0 <8.2.34, >=8.3.0 <8.3.35, >=8.4.0 <8.4.26, and >=8.5.0 <8.5.11, with fixes available in versions 8.2.34, 8.3.35, 8.4.26, and 8.5.11.

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 29 Oct 2026, 13:17 UTC

Technical details

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