CVE-2026-94300 PUBLISHED

Concurrent GSS-TSIG messages corrupt memory

Assigner: isc
Reserved: 21.09.2026 Published: 21.10.2026 Updated: 21.10.2026

Replaying GSS-TSIG signed UDP messages can result in memory corruption in "named". An attacker who can capture a previously signed UDP message can replay it while the negotiated TSIG key is still valid. By also sending crafted queries to a zone the attacker controls, the attacker may potentially achieve remote code execution. This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.29, 9.21.0 through 9.21.26, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.29-S1.

Metrics

CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS Score: 8.1

Product Status

Vendor ISC
Product BIND 9
Versions Default: unaffected
  • affected from 9.11.0 to 9.18.50 (incl.)
  • affected from 9.20.0 to 9.20.29 (incl.)
  • affected from 9.21.0 to 9.21.26 (incl.)
  • affected from 9.11.3-S1 to 9.18.50-S1 (incl.)
  • affected from 9.20.9-S1 to 9.20.29-S1 (incl.)

Exploits

We are not aware of any active exploits.

Workarounds

No workarounds known.

Solutions

Upgrade to the patched release most closely related to your current version of BIND 9: 9.20.30, 9.21.27, or 9.20.30-S1.

Credits

  • While this flaw was discovered in internal testing, ISC would like to thank Dave Aitel from OpenAI who independently discovered and responsibly reported the issue to ISC.

References

Problem Types

  • CWE-415 Double Free CWE
  • CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition) CWE

Impacts

  • Memory corruption, leading to program abort and/or potential remote code execution.