# SixLabors ImageSharp Has Infinite Loop in GIF Decoder When Skipping Malformed Comment Extension Blocks

Advisory record · `GHSA-rxmq-m78w-7wmc`

- **Identifiers:** `GHSA-rxmq-m78w-7wmc` · `CVE-2025-54575`
- **State:** Confirmed
- **Severity:** CVSS 5.3 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-400](https://cwe.mitre.org/data/definitions/400.html) · [CWE-770](https://cwe.mitre.org/data/definitions/770.html)
- **Tags:** [Denial of service](https://agentprime.io/advisories/tag/dos.md)
- **Published:** 30 Jul 2025
- **Updated:** 31 Jul 2025
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 30 Jul 2025, 13:23 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `SixLabors.ImageSharp` (NuGet): affected `<2.1.11 || >=3.0.0, <3.1.11`; fixed in `2.1.11`, `3.1.11`

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> SixLabors.ImageSharp versions before 2.1.11, and versions 3.0.0 up to but not including 3.1.11, are vulnerable. A specially crafted GIF file with a malformed comment extension block, missing its block terminator, can cause the GIF decoder to loop indefinitely, leading to denial of service; the attacker needs only to supply such a file to an application that decodes untrusted GIF input. Upgrade to version 2.1.11 or 3.1.11. No workaround is listed.

Written 9 Nov 2026.

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 5.3 Medium, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0045, the 39th percentile, on 11 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 30 Jul 2025, 09:14 UTC: [Published by the maintainers as a GitHub repository advisory](https://github.com/SixLabors/ImageSharp/security/advisories/GHSA-rxmq-m78w-7wmc)
- 31 Oct 2026, 15:22 UTC: First seen by agentprime
- 31 Oct 2026, 15:22 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-rxmq-m78w-7wmc)

## Sources

- [GitHub Advisory Database: GHSA-rxmq-m78w-7wmc](https://github.com/advisories/GHSA-rxmq-m78w-7wmc)
- [OSV: GHSA-rxmq-m78w-7wmc](https://osv.dev/vulnerability/GHSA-rxmq-m78w-7wmc)
- <https://github.com/SixLabors/ImageSharp/security/advisories/GHSA-rxmq-m78w-7wmc>
- <https://nvd.nist.gov/vuln/detail/CVE-2025-54575>
- <https://github.com/SixLabors/ImageSharp/issues/2953>
- <https://github.com/SixLabors/ImageSharp/commit/55e49262df9a057dff9b7807ed1b7bdb49187c3f>
- <https://github.com/SixLabors/ImageSharp/commit/833f3ceec35af6b775950e06f03b934546cefbf6>
- <https://github.com/SixLabors/ImageSharp>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-rxmq-m78w-7wmc>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-rxmq-m78w-7wmc/>. Everything for agents: <https://agentprime.io/llms.txt>.