CVE-2026-23991Network attack vector

Client crash via unchecked metadata type assertions

Published Jan 22, 2026 · Updated Jan 22, 2026

Denial of service in The Update Framework go-tuf 2.0.0 through 2.3.0 allows remote attackers controlling metadata delivery to crash clients. The metadata.checkType function directly asserts that the untrusted signed field is an object and its _type member is a string, so malformed values cause a Go panic before signature validation. Exploitation requires control of a repository, mirror, or cache response and can place long-running clients in a crash-restart loop without a signing key.

CVSS severity5.9
Medium
EPSS probability0.55%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in The Update Framework go-tuf 2.0.0 through 2.3.0 allows remote attackers controlling metadata delivery to crash clients. The metadata.checkType function directly asserts that the untrusted signed field is an object and its _type member is a string, so malformed values cause a Go panic before signature validation. Exploitation requires control of a repository, mirror, or cache response and can place long-running clients in a crash-restart loop without a signing key.

The record

CVE
CVE-2026-23991
Published
Jan 22, 2026
Updated
Jan 22, 2026
Vendor
The Update Framework
Product
go-tuf
Classifications
CWE-617, CWE-754, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 22, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 22, 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, < 2.3.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Update Framework · go-tufversion=>= 2.0.0, < 2.3.1

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.9GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

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

Weakness, pattern, technique

CWE-617Reachable Assertion
CWE-754Improper Check for Unusual or Exceptional Conditions
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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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