LEONT Perl up to 5.45.1 Regex Engine S_regmatch out-of-bounds

Summaryinfo

A vulnerability has been found in LEONT Perl up to 5.45.1 and classified as critical. This affects the function S_regmatch of the component Regex Engine. Performing a manipulation results in out-of-bounds. This vulnerability is known as CVE-2026-15534. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability was found in LEONT Perl up to 5.45.1. It has been classified as critical. This affects the function S_regmatch of the component Regex Engine. The manipulation with an unknown input leads to a out-of-bounds vulnerability. CWE is classifying the issue as CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

Perl versions through 5.45.1 have out-of-bounds heap reads and writes during regular expression matching via an undersized superlinear cache in S_regmatch. The regex engine's superlinear cache holds one bit per subject position for each participating WHILEM node, so the bit count is the subject length plus one times the number of nodes. Nothing checks that product for positive overflow of the signed 32-bit count: a 286331153 byte subject matched against a pattern with 15 participating nodes stores the count as 14, leaving a two byte cache. The cache is then indexed from the real match position and node number, so reads go past the end of the allocation, and on failure CACHEsayNO sets a bit past it. A caller that matches an attacker controlled subject of this size against a pattern of this shape can crash the process or corrupt heap memory.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-15534 since 07/12/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details are known, but no exploit is available.

Applying the patch 568e6fd238867bb9e99fa3f47cba3169009239e0 is able to eliminate this problem.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-54935). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Type

• Programming Language Software

Vendor

• LEONT

Name

• Perl

Version

• 5.45.0
• 5.45.1

License

• open-source

CPE 2.3info

• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Discussion