CVE-2026-31431: linux-azure, linux-azure-5.4, linux-azure-fips vulnerabilities
Affects Linux kernelSource GCVE Database
Mentioned vulnerabilities
Exploited in the wild · KEV due 15 May 2026 · public exploit available (Metasploit) · 98% EPSS · fixed in 5.4.0-1163.169~18.04.1 : patch Linux kernel now.
Data as of 4 Nov 2026, 22:22 UTC
Actively exploited
High severity · No CVSS score from NVD or the CNA
- KEV deadline
- US federal agencies must patch by this date; a sensible deadline for everyone else. Other KEV due dates
- EPSS
- 98.1% chance of exploitation in 30 days – higher than 99% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 5.4.0-1163.169~18.04.1, 5.4.0-1163.169, 5.4.0-1163.169+fips1
Exploitation evidence
t = 0 is the CVE’s publication on cve.org
Disclosed: evidence found.
CVE published 22 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: evidence found.
Exploited in the wildExploited: evidence found.
Listed in CISA KEV 21 days before disclosure
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
Timeline
Added to CISA KEV (opens in a new tab)
exploitation confirmed
, 21 days before disclosure
KEV remediation due
US federal deadline
, 7 days before disclosure
CVE published
on cve.org
, t = 0
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CISA KEV (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 4 Nov 2026.
What to do
Upgrade the Ubuntu to 5.4.0-1163.169~18.04.1 (linux-azure-5.4 package) or 5.4.0-1163.169 (linux-azure package) or 5.4.0-1163.169+fips1 (linux-azure-fips package).
Patches and advisories
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu Pro 20.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=esm-infra/focalOther threats | Affected
| Fixed in
|
Ubuntu Pro FIPS-updates 20.04 LTSlinux-azure-fipspkg:deb/ubuntu/linux-azure-fips?arch=source&distro=fips-updates/focalOther threats | Affected
| Fixed in
|
Ubuntu Pro 18.04 LTSlinux-azure-5.4pkg:deb/ubuntu/linux-azure-5.4?arch=source&distro=esm-infra/bionicOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
The Linux kernel algif_aead module contains a vulnerability known as Copy Fail, where in-place cryptographic operations are improperly handled. This flaw allows a local attacker to escalate privileges or potentially escape a container. Multiple other security issues affecting the Linux kernel's Cryptographic API, Packet sockets, and TLS protocol were also addressed. These vulnerabilities affect various linux-azure kernel versions and have been fixed in updated releases. A system reboot is required after applying the updates, and third-party kernel modules must be recompiled due to ABI changes.
References
- ubuntu.com/security/notices/USN-8280-2 (opens in a new tab)
- ubuntu.com/security/CVE-2026-31431 (opens in a new tab)
- ubuntu.com/security/CVE-2026-31504 (opens in a new tab)
- ubuntu.com/security/CVE-2026-31533 (opens in a new tab)
- ubuntu.com/security/CVE-2026-43033 (opens in a new tab)
- ubuntu.com/security/CVE-2026-43077 (opens in a new tab)
- ubuntu.com/security/CVE-2026-43078 (opens in a new tab)