Bug 2492973 (CVE-2026-12844)

Summary: CVE-2026-12844 perl-List-SomeUtils-XS: List::SomeUtils::XS: Heap buffer overflow in pairwise() function leading to arbitrary code execution
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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A flaw was found in List::SomeUtils::XS. This vulnerability, a heap buffer overflow, occurs within the `pairwise()` function. When a block call returns more than four times the current memory allocation, it causes data to be written beyond the intended buffer, corrupting the heap. This heap corruption can lead to arbitrary code execution, allowing an attacker to execute malicious code on the affected system.
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Description OSIDB Bzimport 2026-06-25 16:02:06 UTC 
List::SomeUtils::XS versions before 0.59 for Perl have a heap buffer overflow in the pairwise function.

pairwise() collects the values returned by the block into a heap buffer sized to the longer input array, then grows the buffer before each copy with a single quadrupling (alloc <<= 2) instead of a loop. A block call that returns more than four times the current allocation in one invocation outgrows that one quadrupling, and the copy writes past the end of the buffer.

Any caller of pairwise() whose block returns, for a single pair, more than four times the longer input array's length writes past the buffer and corrupts the heap.