CVE-2026-48791Public exploit

Expired-certificate artifact acceptance via omitted time validation

Published Aug 12, 2026 · Updated Aug 12, 2026

Improper bundle verification in Sigstore sigstore-java 2.0.0 allows local users to create signatures accepted after certificate expiry. KeylessVerifier uses a Rekor V1 integratedTime without confirming that it falls within the Fulcio certificate's validity period. Exploitation requires access to a signer's system and theft of its temporary private key, enabling later artifact signing without the signer's credentials.

CVSS severity2.0
Low
EPSS probability0.08%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper bundle verification in Sigstore sigstore-java 2.0.0 allows local users to create signatures accepted after certificate expiry. KeylessVerifier uses a Rekor V1 integratedTime without confirming that it falls within the Fulcio certificate's validity period. Exploitation requires access to a signer's system and theft of its temporary private key, enabling later artifact signing without the signer's credentials.

The record

CVE
CVE-2026-48791
Published
Aug 12, 2026
Updated
Aug 12, 2026
Vendor
Sigstore
Product
sigstore-java
Classifications
CWE-347, T1553.002
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Aug 12, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 12, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion== 2.0.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

Sigstore · sigstore-javaversion== 2.0.0

Published CVSS scores

2.0GitHubCVSS:3.1/AV:L/AC:L/PR:H/UI:R/S:U/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesadmin
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature
T1553.002Subvert Trust Controls: Code Signing

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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