USN-8954-1: zlib vulnerability

Published Oct 22, 2026
·
Updated

Ali Firas discovered that zlib incorrectly handled certain non-blocking write operations. An attacker could possibly use this issue to trigger a heap buffer overflow, resulting in a denial of service or arbitrary code execution.

Affected Software

49 affected componentsFixes available
zlib zlib
All of the following
ubuntu/lib32z1<1:1.3.dfsg+really1.3.2-3ubuntu1.1
1:1.3.dfsg+really1.3.2-3ubuntu1.1
Ubuntu Ubuntu=26.10
All of the following
ubuntu/lib32z1-dev<1:1.3.dfsg+really1.3.2-3ubuntu1.1
1:1.3.dfsg+really1.3.2-3ubuntu1.1
Ubuntu Ubuntu=26.10
All of the following
ubuntu/lib64z1<1:1.3.dfsg+really1.3.2-3ubuntu1.1
1:1.3.dfsg+really1.3.2-3ubuntu1.1
Ubuntu Ubuntu=26.10
All of the following
ubuntu/lib64z1-dev<1:1.3.dfsg+really1.3.2-3ubuntu1.1
1:1.3.dfsg+really1.3.2-3ubuntu1.1
Ubuntu Ubuntu=26.10
All of the following
ubuntu/libx32z1<1:1.3.dfsg+really1.3.2-3ubuntu1.1
1:1.3.dfsg+really1.3.2-3ubuntu1.1
Ubuntu Ubuntu=26.10
All of the following
ubuntu/libx32z1-dev<1:1.3.dfsg+really1.3.2-3ubuntu1.1
1:1.3.dfsg+really1.3.2-3ubuntu1.1
Ubuntu Ubuntu=26.10
All of the following
ubuntu/zlib1g<1:1.3.dfsg+really1.3.2-3ubuntu1.1
1:1.3.dfsg+really1.3.2-3ubuntu1.1
Ubuntu Ubuntu=26.10
All of the following
ubuntu/zlib1g-dev<1:1.3.dfsg+really1.3.2-3ubuntu1.1
1:1.3.dfsg+really1.3.2-3ubuntu1.1
Ubuntu Ubuntu=26.10
All of the following
ubuntu/lib32z1<1:1.3.dfsg+really1.3.1-1ubuntu3.2
1:1.3.dfsg+really1.3.1-1ubuntu3.2
Ubuntu Ubuntu=26.04
All of the following
ubuntu/lib32z1-dev<1:1.3.dfsg+really1.3.1-1ubuntu3.2
1:1.3.dfsg+really1.3.1-1ubuntu3.2
Ubuntu Ubuntu=26.04
All of the following
ubuntu/lib64z1<1:1.3.dfsg+really1.3.1-1ubuntu3.2
1:1.3.dfsg+really1.3.1-1ubuntu3.2
Ubuntu Ubuntu=26.04
All of the following
ubuntu/lib64z1-dev<1:1.3.dfsg+really1.3.1-1ubuntu3.2
1:1.3.dfsg+really1.3.1-1ubuntu3.2
Ubuntu Ubuntu=26.04
All of the following
ubuntu/libx32z1<1:1.3.dfsg+really1.3.1-1ubuntu3.2
1:1.3.dfsg+really1.3.1-1ubuntu3.2
Ubuntu Ubuntu=26.04
All of the following
ubuntu/libx32z1-dev<1:1.3.dfsg+really1.3.1-1ubuntu3.2
1:1.3.dfsg+really1.3.1-1ubuntu3.2
Ubuntu Ubuntu=26.04
All of the following
ubuntu/zlib1g<1:1.3.dfsg+really1.3.1-1ubuntu3.2
1:1.3.dfsg+really1.3.1-1ubuntu3.2
Ubuntu Ubuntu=26.04
All of the following
ubuntu/zlib1g-dev<1:1.3.dfsg+really1.3.1-1ubuntu3.2
1:1.3.dfsg+really1.3.1-1ubuntu3.2
Ubuntu Ubuntu=26.04
All of the following
ubuntu/lib32z1<1:1.3.dfsg-3.1ubuntu2.3
1:1.3.dfsg-3.1ubuntu2.3
Ubuntu Ubuntu=24.04
All of the following
ubuntu/lib32z1-dev<1:1.3.dfsg-3.1ubuntu2.3
1:1.3.dfsg-3.1ubuntu2.3
Ubuntu Ubuntu=24.04
All of the following
ubuntu/lib64z1<1:1.3.dfsg-3.1ubuntu2.3
1:1.3.dfsg-3.1ubuntu2.3
Ubuntu Ubuntu=24.04
All of the following
ubuntu/lib64z1-dev<1:1.3.dfsg-3.1ubuntu2.3
1:1.3.dfsg-3.1ubuntu2.3
Ubuntu Ubuntu=24.04
All of the following
ubuntu/libx32z1<1:1.3.dfsg-3.1ubuntu2.3
1:1.3.dfsg-3.1ubuntu2.3
Ubuntu Ubuntu=24.04
All of the following
ubuntu/libx32z1-dev<1:1.3.dfsg-3.1ubuntu2.3
1:1.3.dfsg-3.1ubuntu2.3
Ubuntu Ubuntu=24.04
All of the following
ubuntu/zlib1g<1:1.3.dfsg-3.1ubuntu2.3
1:1.3.dfsg-3.1ubuntu2.3
Ubuntu Ubuntu=24.04
All of the following
ubuntu/zlib1g-dev<1:1.3.dfsg-3.1ubuntu2.3
1:1.3.dfsg-3.1ubuntu2.3
Ubuntu Ubuntu=24.04

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade ubuntu/lib32z1 to a version that resolves this vulnerability.

    Fixed in 1:1.3.dfsg+really1.3.2-3ubuntu1.1
  2. Upgrade

    Upgrade ubuntu/lib32z1-dev to a version that resolves this vulnerability.

    Fixed in 1:1.3.dfsg+really1.3.2-3ubuntu1.1
  3. Upgrade

    Upgrade ubuntu/lib64z1 to a version that resolves this vulnerability.

    Fixed in 1:1.3.dfsg+really1.3.2-3ubuntu1.1
  4. Upgrade

    Upgrade ubuntu/lib64z1-dev to a version that resolves this vulnerability.

    Fixed in 1:1.3.dfsg+really1.3.2-3ubuntu1.1
  5. Upgrade

    Upgrade ubuntu/libx32z1 to a version that resolves this vulnerability.

    Fixed in 1:1.3.dfsg+really1.3.2-3ubuntu1.1
  6. Upgrade

    Upgrade ubuntu/libx32z1-dev to a version that resolves this vulnerability.

    Fixed in 1:1.3.dfsg+really1.3.2-3ubuntu1.1
  7. Upgrade

    Upgrade ubuntu/zlib1g to a version that resolves this vulnerability.

    Fixed in 1:1.3.dfsg+really1.3.2-3ubuntu1.1
  8. Upgrade

    Upgrade ubuntu/zlib1g-dev to a version that resolves this vulnerability.

    Fixed in 1:1.3.dfsg+really1.3.2-3ubuntu1.1
  9. Upgrade

    Upgrade ubuntu/lib32z1 to a version that resolves this vulnerability.

    Fixed in 1:1.3.dfsg+really1.3.1-1ubuntu3.2
  10. Upgrade

    Upgrade ubuntu/lib32z1-dev to a version that resolves this vulnerability.

    Fixed in 1:1.3.dfsg+really1.3.1-1ubuntu3.2
  11. Upgrade

    Upgrade ubuntu/lib64z1 to a version that resolves this vulnerability.

    Fixed in 1:1.3.dfsg+really1.3.1-1ubuntu3.2
  12. Upgrade

    Upgrade ubuntu/lib64z1-dev to a version that resolves this vulnerability.

    Fixed in 1:1.3.dfsg+really1.3.1-1ubuntu3.2
  13. Upgrade

    Upgrade ubuntu/libx32z1 to a version that resolves this vulnerability.

    Fixed in 1:1.3.dfsg+really1.3.1-1ubuntu3.2
  14. Upgrade

    Upgrade ubuntu/libx32z1-dev to a version that resolves this vulnerability.

    Fixed in 1:1.3.dfsg+really1.3.1-1ubuntu3.2
  15. Upgrade

    Upgrade ubuntu/zlib1g to a version that resolves this vulnerability.

    Fixed in 1:1.3.dfsg+really1.3.1-1ubuntu3.2
  16. Upgrade

    Upgrade ubuntu/zlib1g-dev to a version that resolves this vulnerability.

    Fixed in 1:1.3.dfsg+really1.3.1-1ubuntu3.2
  17. Upgrade

    Upgrade ubuntu/lib32z1 to a version that resolves this vulnerability.

    Fixed in 1:1.3.dfsg-3.1ubuntu2.3
  18. Upgrade

    Upgrade ubuntu/lib32z1-dev to a version that resolves this vulnerability.

    Fixed in 1:1.3.dfsg-3.1ubuntu2.3
  19. Upgrade

    Upgrade ubuntu/lib64z1 to a version that resolves this vulnerability.

    Fixed in 1:1.3.dfsg-3.1ubuntu2.3
  20. Upgrade

    Upgrade ubuntu/lib64z1-dev to a version that resolves this vulnerability.

    Fixed in 1:1.3.dfsg-3.1ubuntu2.3
  21. Upgrade

    Upgrade ubuntu/libx32z1 to a version that resolves this vulnerability.

    Fixed in 1:1.3.dfsg-3.1ubuntu2.3
  22. Upgrade

    Upgrade ubuntu/libx32z1-dev to a version that resolves this vulnerability.

    Fixed in 1:1.3.dfsg-3.1ubuntu2.3
  23. Upgrade

    Upgrade ubuntu/zlib1g to a version that resolves this vulnerability.

    Fixed in 1:1.3.dfsg-3.1ubuntu2.3
  24. Upgrade

    Upgrade ubuntu/zlib1g-dev to a version that resolves this vulnerability.

    Fixed in 1:1.3.dfsg-3.1ubuntu2.3

Event History

Oct 22, 2026
Advisory Published
via Ubuntu·12:00 AM
Data Sourced
via Ubuntu·12:00 AM
DescriptionAffected Software

Child vulnerabilities

Contains the following vulnerabilities.

Company

Resources

Contact

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