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Public proof of conceptFix available

CVE-2025-40775

DNS message with invalid TSIG causes an assertion failure

A public proof of concept exists; no exploitation attested.

  • Published2025-05-21
  • WeaknessCWE-232

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

When an incoming DNS protocol message includes a Transaction Signature (TSIG), BIND always checks it. If the TSIG contains an invalid value in the algorithm field, BIND immediately aborts with an assertion failure. This issue affects BIND 9 versions 9.20.0 through 9.20.8 and 9.21.0 through 9.21.7.

Timeline

dates in UTC
  1. 2025-05-2113:16CVE publishedNVD

Versions per branch

Products declared by the CNA1 product

As isc, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • ISC BIND 9other versions: not affected
    Affected
    • ≥ 9.20.0, ≤ 9.20.8no fix statedcustom
    • ≥ 9.21.0, ≤ 9.21.7no fix statedcustom

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2025-05-21

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • bindSUSE:Linux Enterprise Module for Server Applications 15 SP7all versions · fixed in 9.20.9-150700.3.3.1
  • bindSUSE:Linux Enterprise Module for Basesystem 15 SP7all versions · fixed in 9.20.9-150700.3.3.1
  • bindopenSUSE:Tumbleweedall versions · fixed in 9.20.9-1.1
  • bindAzure Linux:3all versions · fixed in 9.20.9-1
  • bindAlpine:v3.24all versions · fixed in 9.20.9-r0
  • bindAlpine:v3.23all versions · fixed in 9.20.9-r0
  • bindAlpine:v3.22all versions · fixed in 9.20.9-r0
  • bindAlpine:v3.21all versions · fixed in 9.18.37-r0

7 more package ranges on OSV.dev

Vendor advisories

  • CVE-2025-40775 Red Hat Product Security

    bind: DNS message with invalid TSIG causes an assertion failure

Full record on NVD

Fix

No fix published by the sources we read yet. NVD record

Detection

read 2026-11-01 01:02 UTC
Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published
2025-05-21
Last Modified
2026-06-17
NVD status
Deferred
GitHub Advisory
GHSA-gqgx-hgvf-f75f

Frequently asked questions

What is CVE-2025-40775?

When an incoming DNS protocol message includes a Transaction Signature (TSIG), BIND always checks it. If the TSIG contains an invalid value in the algorithm field, BIND immediately aborts with an assertion failure. This issue affects BIND 9 versions 9.20.0 through 9.20.8 and 9.21.0 through 9.21.7.

Is CVE-2025-40775 actively exploited?

Active exploitation of CVE-2025-40775 has not been confirmed. Its EPSS score was 15.3% on 2026-11-09, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2025-40775?

CVE-2025-40775 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

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