# CVE-2026-129113: JSON::XS versions from 4.0_00 before 4.05 for Perl corrupt the incremental buffer length by chopping past its end in incr_skip after a top-level number

Status: published. Published: 2026-11-14. Updated: 2026-11-14.

JSON::XS versions from 4.0_00 before 4.05 for Perl corrupt the incremental buffer length by chopping past its end in incr_skip after a top-level number.

The incremental parser scans any run of digits, signs, dots and exponent markers as one number, but the decoder stops at the end of a valid number, so the parser keeps an offset into bytes it has not decoded. It then empties the buffer without clearing those bytes, and a later incr_parse call without new input reads them again and moves the offset past the end of the buffer. incr_skip, the documented recovery after an error, removes that many bytes and the buffer length wraps.

A peer sending input such as "1-2" to an incr_parse consumer can make the next read of incr_text exit the process through perl's uncatchable out-of-memory path.

## Remediation

- fix: Upgrade to JSON-XS 4.05 or later. (source: CNA: CPANSec)

## Affected products and versions

-  /  (JSON-XS): ≥ 4.0_00; < 4.05 (affected, custom). Source: CNA: CPANSec

## Severity and prioritization

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-191

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://metacpan.org/release/MLEHMANN/JSON-XS-4.05/changes (CNA: CPANSec; release-notes)

## Provenance

- CNA: CPANSec: https://www.cve.org/CVERecord?id=CVE-2026-129113; retrieved 2026-11-14; source updated 2026-11-14

Revision: 2b7aaec5f18cc3266c6015a578606f8e88e648ef5fa56e8b7a7a5b31ba2c7d37

Canonical: https://y2.dev/cve/CVE-2026-129113

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