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Not in CISA KEV
NONE severity

CVE-2026-24408 — sigstore

NONEFix: sigstore/sigstore-python@5e77497

CVE-2026-24408 is a none-severity (CVSS 0) Cross-Site Request Forgery (CSRF) vulnerability in sigstore. A fix is available for sigstore — see the affected versions and patch details below.

sigstore has CSRF possibility in OIDC authentication during signing

Also known asGHSA-hm8f-75xx-w2vrPYSEC-2026-1924
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • 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 CVE-2026-24408.

EPSS Exploitation Probability

via FIRST.org ↗
0.2%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs7th percentile — riskier than 7% of all scored CVEsHighest risk
0.00%0.23%0.45%0.68%0.0%0.2%May 26Sep 26Nov 26

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

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
🐍sigstore

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

Summary

The sigstore-python OAuth authentication flow is susceptible to Cross-Site Request Forgery.

Details

_OAuthSession creates a unique "state" and sends it as a parameter in the authentication request but the "state" in the server response seems not not be cross-checked with this value.

Fix should be fairly trivial.

Impact

This should be low impact: A man-in-the middle attacker could trick a sigstore-python user into signing something with an identity controlled by the attacker (by returning the response to an authentication request they created). This would be quite confusing but not dangerous.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐍PyPIsigstoreall versions4.2.0pip install --upgrade 'sigstore==4.2.0'

Affected Products

1 product · 1 configurations
Application
sigstore-pythonlinuxfoundation
< 4.2.0
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

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

  2. Fix

    Update sigstore to 4.2.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-24408 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

### Summary The sigstore-python OAuth authentication flow is susceptible to Cross-Site Request Forgery. ### Details `_OAuthSession` creates a unique "state" and sends it as a parameter in the authentication request but the "state" in the server response seems not not be cross-checked with this value. Fix should be fairly trivial. ### Impact This should be low impact: A man-in-the middle attacker could trick a sigstore-python user into signing something with an identity controlled by the attacker (by returning the response to an authentication request they created). This would be quite c
O3 Security · Impact-Aware SCA

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CVE-2026-24408: sigstore CSRF — Fixed in 4.2.0