CVE-2024-55655 sigstore-python has insufficient validation of integration timestamp during verification
Attackers can manipulate integration timestamps in Sigstore bundles, potentially causing denial of service, though other controls prevent signature impersonation.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2024-55655?
CVE-2024-55655 is a low-severity vulnerability in sigstore-python, published on 10 Dec 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
sigstore-python is a Python tool for generating and verifying Sigstore signatures. Versions of sigstore-python newer than 2.0.0 but prior to 3.6.0 perform insufficient validation of the "integration time" present in "v2" and "v3" bundles during the verification flow: the "integration time" is verified *if* a source of signed time (such as an inclusion promise) is present, but is otherwise trusted if no source of signed time is present. This does not affect "v1" bundles, as the "v1" bundle format always requires an inclusion promise.
Sigstore uses signed time to support verification of signatures made against short-lived signing keys. The impact and severity of this weakness is *low*, as Sigstore contains multiple other enforcing components that prevent an attacker who modifies the integration timestamp within a bundle from impersonating a valid signature. In particular, an attacker who modifies the integration timestamp can induce a Denial of Service, but in no different manner than already possible with bundle access (e.g. modifying the signature itself such that it fails to verify). Separately, an attacker could upload a *new* entry to the transparency service, and substitute their new entry's time. However, this would still be rejected at validation time, as the new entry's (valid) signed time would be outside the validity window of the original signing certificate and would nonetheless render the attacker auditable.
Which versions are affected by CVE-2024-55655?
3 open source packages ship an affected version, including sigstore.
| Package | Affected | Fixed in |
|---|---|---|
sigstore PyPI | From 2.0.0 | 3.6.0 |
sigstore PyPI | From 2.0.0 | 3.6.0 |
sigstore PyPI | From 2.0.0 | 3.6.0 |
How do I fix CVE-2024-55655?
Upgrade sigstore to 3.6.0 or later.
Is CVE-2024-55655 being exploited?
There is no known exploitation of CVE-2024-55655 in the wild and no public exploit code.
Sources
Also known as GHSA-hhfg-fwrw-87w7, PYSEC-2026-1923.