GHSA-hhfg-fwrw-87w7: sigstore (CVE-2024-55655)

Package	Ecosystem	Affected	Fixed in
sigstore	PyPI	>=2.0.0, <3.6.0	3.6.0

Machine-written summary

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

Versions of sigstore from 2.0.0 up to but not including 3.6.0 insufficiently validate the integration timestamp in v2 and v3 bundles during verification. The timestamp is only checked when a source of signed time, such as an inclusion promise, is present; otherwise it is trusted. An attacker who can modify a bundle could alter the timestamp, but the source reports the impact as low, mainly causing denial of service, since other checks still reject forged signatures. Upgrade to sigstore 3.6.0 or later.

Written 5 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

Score	Rating	CVSS	Vector	Source
2.7	Low	4.0	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U	CNA (GitHub_M)

CISA KEV Not listed.
EPSS 0.0025, the 16th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

31 Oct 2026, 14:35 UTC First seen by agentprime
31 Oct 2026, 14:35 UTC Confirmed by OSV

Sources

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.