Fix heap-use-after-free in _decode_entities (CVE-2026-8829)#56
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When the input SV passed to _decode_entities is the same SV stored as a self-referential value in the entity hash, grow_gap() could realloc the SV's PV buffer, leaving repl pointing at freed memory. Copy the entity value into an owned buffer when the hash entry SV aliases the input SV. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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Summary
Fixes a heap-use-after-free in
_decode_entities(CVE-2026-8829).When the input SV passed to
_decode_entitiesis the same SV stored as a self-referential value in the entity hash,grow_gap()could realloc the SV's PV buffer, leavingreplpointing at freed memory. The fix copies the entity value into an owned buffer when the hash entry SV aliases the input SV, soreplstays valid after a later realloc.The change is by Paul Johnson, who supplied it as a diff.
Test plan
t/entities.texercises_decode_entitieswith a self-aliased entity hash value and a payload large enough to forcegrow_gap()to realloc the SV's PV.🤖 Generated with Claude Code