CVE-2026-129114
JSON::XS versions from 3.04 before 4.05 for Perl write one byte past a heap buffer when appending a one-byte chunk in incr_parse
Description
JSON::XS versions from 3.04 before 4.05 for Perl write one byte past a heap buffer when appending a one-byte chunk in incr_parse. The incremental buffer grows to one and a half times the length it must hold, with no room reserved for the terminating NUL. For an empty buffer and a one-byte chunk that request is one byte, which a buffer whose front was removed by earlier decodes can already have, so nothing is reallocated and the NUL lands one byte past the allocation. A peer streaming data to an incr_parse consumer, choosing how the input is split into reads, can cause a one-byte heap out-of-bounds write.
Key facts
- Published
- 14 Nov 2026
- Last changed
- 14 Nov 2026
- Assigned by
- CPANSec
- EPSS
- 0.204% likely to be exploited in the next 30 days, higher than 10.442% of CVEs (scores for 15 Nov 2026)
What to do
- Upgrade to JSON-XS 4.05 or later.CNA solution statement
Historical context and remediation
This reference retains the original CVE publication date. A recent record update does not mean a new attack occurred.
No separately sourced impact summary is available on this page yet. Consult the description, version data and dated exploitation evidence.
Version statuses below come from the CNA. An “unaffected” version is not necessarily a currently supported release or proof of a patch date. EPSS is a dated risk estimate, not a count of historical attacks.
Timeline
- 13 Nov 2026 Version 4.05 released with fix.
- 14 Nov 2026 Published