CVE-2026-15534
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
Description
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.
INFO
Published Date :
Aug. 9, 2026, 6:16 p.m.
Last Modified :
Sept. 8, 2026, 10:17 p.m.
Remotely Exploit :
No
Source :
9b29abf9-4ab0-4765-b253-1875cd9b441e
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | 134c704f-9b21-4f2e-91b3-4a467353bcc0 |
Solution
- Update Perl to a patched version.
- Avoid processing untrusted regex patterns.
- Validate subject string lengths.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-15534.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-15534 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-15534
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-15534 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-15534 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 9b29abf9-4ab0-4765-b253-1875cd9b441e
Sep. 08, 2026
Action Type Old Value New Value Added Affected Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/15xxx/CVE-2026-15534.json">CVE-2026-15534</a> Added Reference https://github.com/Perl/perl5/commit/54cf3d44cbbedd17d774e9a37921963e8fd5d0cb.patch Added Reference https://github.com/Perl/perl5/commit/568e6fd238867bb9e99fa3f47cba3169009239e0.patch Removed Reference https://github.com/Perl/perl5/commit/54cf3d44cbbedd17d774e9a37921963e8fd5d0cb.patch Removed Reference https://github.com/Perl/perl5/commit/568e6fd238867bb9e99fa3f47cba3169009239e0.patch -
CVE Modified by af854a3a-2127-422b-91ae-364da2661108
Sep. 08, 2026
Action Type Old Value New Value Added Reference http://www.openwall.com/lists/oss-security/2026/08/09/12 Added Reference http://www.openwall.com/lists/oss-security/2026/08/09/13 Removed Reference http://www.openwall.com/lists/oss-security/2026/08/09/12 Removed Reference http://www.openwall.com/lists/oss-security/2026/08/09/13 -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Aug. 12, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H Added SSVC {'id': 'CVE-2026-15534', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-08-12T17:38:23.129391Z'} -
CVE Modified by af854a3a-2127-422b-91ae-364da2661108
Aug. 09, 2026
Action Type Old Value New Value Added Reference http://www.openwall.com/lists/oss-security/2026/08/09/13 -
CVE Modified by af854a3a-2127-422b-91ae-364da2661108
Aug. 09, 2026
Action Type Old Value New Value Added Reference http://www.openwall.com/lists/oss-security/2026/08/09/12 -
New CVE Received by 9b29abf9-4ab0-4765-b253-1875cd9b441e
Aug. 09, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://github.com/Perl/perl5', 'vendor': 'LEONT', 'product': 'perl', 'versions': [{'status': 'affected', 'version': '0', 'versionType': 'custom', 'lessThanOrEqual': '5.45.1'}], 'packageName': 'perl', 'programFiles': ['regexec.c'], 'collectionURL': 'https://cpan.org/modules', 'defaultStatus': 'unaffected', 'programRoutines': [{'name': 'S_regmatch'}]}] Added Description 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. Added CWE CWE-125 Added CWE CWE-787 Added CWE CWE-190 Added Reference https://github.com/Perl/perl5/commit/54cf3d44cbbedd17d774e9a37921963e8fd5d0cb.patch Added Reference https://github.com/Perl/perl5/commit/568e6fd238867bb9e99fa3f47cba3169009239e0.patch