CVE-2026-80603: Linux kernel · netfilter: nf_conntrack_irc: fix parse_dcc() off-by-one OOB read
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 9.1 Critical · fixed in 5.15.0-1117.124~20.04.1 : patch Linux kernel as a priority.
Data as of 26 Oct 2026, 13:47 UTC
- EPSS
- 0.5% chance of exploitation in 30 days – higher than 48% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 5.15.0-1117.124~20.04.1, 5.15.0-1123.132~20.04.1, 5.15.0-1122.131~20.04.1 +40
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:NExploitation evidence
Disclosed: evidence found.
CVE published 28 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A patch is available that corrects the loop condition in parse_dcc() to prevent the out-of-bounds read. Users should apply the official Linux kernel updates that address this issue. The vendor advisory confirms the availability of fixes. No additional mitigation steps are indicated.
Description
A vulnerability in the Linux kernel's netfilter nf_conntrack_irc module was fixed. The flaw is an off-by-one out-of-bounds read in the parse_dcc() function, where the code incorrectly treats an exclusive end pointer as inclusive, potentially causing a read of uninitialized memory. This can lead to incorrect parsing of DCC IP or port values. The issue was addressed by correcting the loop condition to use a strict less-than comparison consistent with the caller's convention.
References
- nvd.nist.gov/vuln/detail/CVE-2026-80603 (opens in a new tab)
- git.kernel.org/stable/c/2393f0bd7a467ad475598f3a5b9de27ca36e3037 (opens in a new tab)
- git.kernel.org/stable/c/2b70f61f569bb29acb380e6f616a1bbdee15668f (opens in a new tab)
- git.kernel.org/stable/c/437e0a3854b3a44ec15afa9ab88ec215adf3a2fd (opens in a new tab)
- git.kernel.org/stable/c/910c33e4a8c046c3cc1fa5a465a4d41a1bb398f1 (opens in a new tab)
- git.kernel.org/stable/c/abb8c32b88ea3f46beb68c34fe9a3ac8ed664e7e (opens in a new tab)
- git.kernel.org/stable/c/aff589556ed772cb1c0c2d7b4d91ec45c0c39416 (opens in a new tab)
- git.kernel.org/stable/c/eeef3b81f449560653662df2dde6f6fe247c5365 (opens in a new tab)
- git.kernel.org/stable/c/ef6400ca25a13fd6dedbe8ef4a1d0979bbbfe88a (opens in a new tab)
- ubuntu.com/security/CVE-2026-80603 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-80603 (opens in a new tab)
- git.kernel.org/linus/ef6400ca25a13fd6dedbe8ef4a1d0979bbbfe88a (opens in a new tab)
- ubuntu.com/security/notices/USN-8878-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8879-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8877-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8875-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8888-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8889-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8887-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8888-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8887-2 (opens in a new tab)