5.3

CVE-2026-39395: sigstore cosign

CVSS: 5.3v3.1MediumAnalyzed
AliasesSUSE-SU-2026:22344-1SUSE-SU-2026:2365-1UBUNTU-CVE-2026-39395
Published 07-04-2026Last modified 08-04-2026
Open JSON

Vulnerability summary

CVE-2026-39395 is a medium (CVSS 5.3) vulnerability in sigstore cosign. EPSS estimates a 0.29% chance of exploitation in the next 30 days, higher than 20.5% of scored vulnerabilities.

Overall risk
21/100
0100
Low · default modelHow is this calculated?
CVSS score
5.3/10
010
Medium · v3.1 (NVD)
EPSS score
0.29%
0%100%
Low · +0.05 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 1 · Related 2
OPENSUSE-SU-2026:21483-1CGA-PPCM-JCWG-GWM4

Timeline

  1. 07-04-2026
    PublishedVulnerability first disclosed.
  2. 08-04-2026
    Last modifiedVulnerability information updated.

Description

Cosign provides code signing and transparency for containers and binaries. Prior to 3.0.6 and 2.6.3, cosign verify-blob-attestation may erroneously report a "Verified OK" result for attestations with malformed payloads or mismatched predicate types. For old-format bundles and detached signatures, this was due to a logic flaw in the error handling of the predicate type validation. For new-format bundles, the predicate type validation was bypassed completely. This vulnerability is fixed in 3.0.6 and 2.6.3.

CVSS metrics

7 scores · 7 sources · 1 version

EPSS trend

Probability

0.29%

Chance of exploitation in the next 30 days

Percentile

21%

Versus all other CVEs

30-day change

+0.05 pp

From 0.24% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.29%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Chainguard126 products
  • aactl< 0.4.12-r55
  • chainctl< 0.2.295-r1
  • chainctl-fips< 0.2.295-r0
  • cloudbeat-8.17< 8.17.10-r27
  • cloudbeat-9.0< 9.0.8-r30
Wolfi27 products
  • aactl< 0.4.12-r55
  • crossplane-2.1< 2.1.7-r3
  • crossplane-2.2< 2.2.3-r3
  • crossplane-2.2-crank< 2.2.3-r3
  • kubescape< 4.0.9-r5
Suse3 products
  • cosign&distro=SUSE Linux Enterprise Module for Basesystem 15 SP7< 3.0.6-150400.3.42.1
  • cosign&distro=SUSE Linux Enterprise Server 16.0< 3.0.6-160000.1.1
  • cosign&distro=SUSE Linux Enterprise Server for SAP applications 16.0< 3.0.6-160000.1.1
Github.com/sigstore/cosign2 products
  • v2< 2.6.3
  • v3≥ 3.0.0, < 3.0.6
Opensuse2 products
  • cosign&distro=openSUSE Leap 16.0< 3.0.6-160000.1.1
  • cosign&distro=openSUSE Tumbleweed< 3.0.6-1.1
Debian1 product
  • cosignAll versions (No fix recorded) | < 2.6.3-1
Github.com/sigstore1 product
  • cosign≥ 3.0.0, < 3.0.6 | < 2.6.3 | All versions (No fix recorded)
Sigstore1 product
  • cosign< 2.6.3 | ≥ 3.0.0, < 3.0.6
Ubuntu1 product
  • cosignAll versions (No fix recorded)

9 vendors · 164 products

References

11 links
Show all 11 references