Threats Tagged 'cve-2026-15534'

A vulnerability (CVE-2026-15534) was found in Perl's regular expression engine used in Red Hat Hardened Images. It involves a signed 32-bit integer overflow in the superlinear cache size calculation, which can cause out-of-bounds heap memory reads and writes during regex matching. Exploitation requires matching a very large input (~273 MiB) against a complex pattern with at least 15 participating WHILEM nodes. The primary impact is denial of service due to process crashes; arbitrary code execution has not been demonstrated. Red Hat has deferred fixing this issue due to the high complexity and limited exposure. Mitigations include limiting untrusted input size and avoiding complex regex patterns on untrusted data.

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.