VulnerabilityPublished 10 Jan 2026Updated 12 Jan 2026

CVE-2026-22703: sigstore cosign · Insufficient Verification of Data Authenticity

Affects sigstore cosignSource CVE Database V5

Compare

Not known to be exploited · CVSS 5.5 Medium : upgrade to 3.0.4 or 2.6.2 when convenient.

Data as of 12 Nov 2026, 23:24 UTC

CVSS 3.1 base score

5.5Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.1% chance of exploitation in 30 days – higher than 1% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 3.0.4, 2.6.2

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

Attack Vector: Local
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: High
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Local: The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., tricking a legitimate user into opening a malicious document).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 10 Jan 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 13 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade cosign and github.com/sigstore/cosign to 3.0.4 or 2.6.2.

Affected software

Product	Affected	Fixed in
sigstorecosign	Affected <3.0.4	Fixed in 3.0.4
sigstorecosign	Affected <2.6.2	Fixed in 2.6.2
Gogithub.com/sigstore/cosign`pkg:golang/github.com/sigstore/cosign`Other threats	Affected <2.6.2 <3.0.4	Fixed in 2.6.2 3.0.4

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

European organizations should immediately upgrade cosign to versions 2.6.2 or 3.0.4 or later to ensure the vulnerability is patched. Additionally, organizations should implement strict access controls and monitoring around signing keys and developer environments to prevent credential compromise. Employ hardware security modules (HSMs) or secure key management solutions to protect signing keys and reduce risk of key theft. Integrate continuous monitoring and auditing of signing events and transparency logs to detect anomalies or suspicious Rekor entries. Enforce multi-factor authentication and least privilege principles for users with signing capabilities. Consider implementing additional verification layers or cross-checks in the CI/CD pipeline to validate artifact provenance beyond cosign's built-in checks. Regularly review and update supply chain security policies to incorporate lessons learned from this vulnerability. Finally, educate developers and security teams about the risks of signing key compromise and the importance of timely patching.

Description

Cosign provides code signing and transparency for containers and binaries. Prior to versions 2.6.2 and 3.0.4, Cosign bundle can be crafted to successfully verify an artifact even if the embedded Rekor entry does not reference the artifact's digest, signature or public key. When verifying a Rekor entry, Cosign verifies the Rekor entry signature, and also compares the artifact's digest, the user's public key from either a Fulcio certificate or provided by the user, and the artifact signature to the Rekor entry contents. Without these comparisons, Cosign would accept any response from Rekor as valid. A malicious actor that has compromised a user's identity or signing key could construct a valid Cosign bundle by including any arbitrary Rekor entry, thus preventing the user from being able to audit the signing event. This issue has been patched in versions 2.6.2 and 3.0.4.

Impact

For European organizations, this vulnerability poses a significant risk to the integrity of their software supply chain security, particularly for those leveraging cosign for container and binary signing. If exploited, attackers with access to signing credentials can forge signing bundles that appear legitimate, potentially distributing malicious or tampered software without detection. This undermines trust in signed artifacts and can lead to deployment of compromised software in production environments. While confidentiality and availability are not directly impacted, the integrity breach can have cascading effects, including regulatory compliance violations (e.g., under NIS2 or GDPR if software integrity is part of security controls), reputational damage, and operational disruptions. Organizations in sectors with stringent software supply chain requirements, such as finance, healthcare, and critical infrastructure, are especially vulnerable. The requirement for local privileges limits remote exploitation but does not eliminate risk from insider threats or compromised developer environments.

Summary

Cosign is a tool within the sigstore project designed to provide cryptographic signing and transparency for container images and binaries, enhancing software supply chain security. Prior to versions 2.6.2 and 3.0.4, cosign had a vulnerability (CVE-2026-22703) classified under CWE-345 (Insufficient Verification of Data Authenticity). The vulnerability arises because cosign's verification process for Rekor transparency log entries did not adequately ensure that the Rekor entry referenced the artifact's digest, signature, or public key. Specifically, while cosign verified the Rekor entry's signature, it failed to confirm that the embedded Rekor entry matched the artifact being verified. This allowed an attacker who had compromised a user's signing key or identity to create a cosign bundle containing arbitrary Rekor entries unrelated to the actual artifact. Consequently, the user would be unable to audit or verify the legitimacy of the signing event, as cosign would accept any Rekor response as valid. This flaw undermines the integrity of the signing and transparency mechanism, potentially allowing malicious code to appear as legitimately signed. The vulnerability requires local privileges (AV:L) and low complexity (AC:L) to exploit, with no user interaction (UI:N) needed. The scope is unchanged (S:U), and the impact affects integrity (I:H) but not confidentiality or availability. The issue has been addressed in cosign versions 2.6.2 and 3.0.4 by enforcing strict verification that the Rekor entry corresponds correctly to the artifact's digest, signature, and public key.

CWE-345Insufficient Verification of Data Authenticity (opens in a new tab)
Class weaknessOWASP Top 10 A08:2025: Software or Data Integrity Failures (opens in a new tab)
The product does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
OWASP Cheat Sheets
XML Security (opens in a new tab)
REST Security (opens in a new tab)
JSON Web Token for Java (opens in a new tab)
REST Assessment (opens in a new tab)
Cross-Site Request Forgery Prevention (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.2 (opens in a new tab)
V3.5.3 (opens in a new tab)
V13.2.6 (opens in a new tab)
Attack patterns
JSON Hijacking (aka JavaScript Hijacking) (opens in a new tab)
Cache Poisoning (opens in a new tab)
DNS Cache Poisoning (opens in a new tab)
Spoofing of UDDI/ebXML Messages (opens in a new tab)
Application API Message Manipulation via Man-in-the-Middle (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 17 Jan 2026, 07:55 UTC

WeaknessesCWE-345

Technical details

References

Community reviews

Related threats