How severe is GHSA-fc9g-5qg7-mf45?

No CVSS score has been assigned to GHSA-fc9g-5qg7-mf45 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-fc9g-5qg7-mf45?

GHSA-fc9g-5qg7-mf45 affects the following packages: pillow (PyPI). Ecosystems affected: PyPI.

How do I fix GHSA-fc9g-5qg7-mf45?

Update pillow to 13.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-fc9g-5qg7-mf45 is resolved across your whole dependency graph.

How do I detect GHSA-fc9g-5qg7-mf45 in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pillow, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate GHSA-fc9g-5qg7-mf45 if there is no patch (or I can't update yet)?

Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Is GHSA-fc9g-5qg7-mf45 actively exploited in the wild?

No public exploit code has been indexed for GHSA-fc9g-5qg7-mf45 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-fc9g-5qg7-mf45?

GHSA-fc9g-5qg7-mf45 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 30th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-fc9g-5qg7-mf45?

GHSA-fc9g-5qg7-mf45 is classified as CWE-407 (CWE-407). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-fc9g-5qg7-mf45 published, and has it been updated?

GHSA-fc9g-5qg7-mf45 was published on October 21, 2026 and was last updated on October 21, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍 PyPI

Not in CISA KEV

Pillow: Quadratic GIF comment copying during saveGHSA-fc9g-5qg7-mf45

Fix: python-pillow/Pillow@68a3fe9

GHSA-fc9g-5qg7-mf45 is a CWE-407 vulnerability in pillow. A fix is available for pillow — see the affected versions and patch details below.

Also known asCVE-2026-112891

Published

Oct 21, 2026

Updated

Oct 21, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 21, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-fc9g-5qg7-mf45.

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs30th percentile — riskier than 30% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected

🐍pillow

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

On Pillow 12.3.0 and upstream main (ad277e2761b489681e71b51e91367d46b0ceabb9), a GIF with a long comment makes _get_global_header() copy portions of the comment repeatedly when saving, including comments carried over from untrusted images. I suggest provisional Moderate severity for crafted-image CPU denial of service, with CVSS-B 6.9 assuming a network service automatically opens unauthenticated uploads and they are resaved as GIFs; impact depends on input-size, concurrency, and worker CPU limits.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`pillow`	≥ 9.2.0&&< 13.0.0	13.0.0`pip install --upgrade 'pillow==13.0.0'`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pillow, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update pillow to 13.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-fc9g-5qg7-mf45 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Frequently Asked Questions

On Pillow 12.3.0 and upstream `main` (`ad277e2761b489681e71b51e91367d46b0ceabb9`), a GIF with a long comment makes `_get_global_header()` copy portions of the comment repeatedly when saving, including comments carried over from untrusted images. I suggest provisional **Moderate** severity for crafted-image CPU denial of service, with CVSS-B 6.9 assuming a network service automatically opens unauthenticated uploads and they are resaved as GIFs; impact depends on input-size, concurrency, and worker CPU limits.

O3 Security · Impact-Aware SCA

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