Look up another CVE · open CVE-2026-53268 in the interactive tracker
CVE-2026-53268
netfilter: conntrack_irc: fix possible out-of-bounds read
Published 2026-06-25 (4 months ago) by the Linux kernel CNA. Subsystem net/netfilter. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-53268 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | fixedDLA-4665-1 · 2026-07-03 · text | 6.1.176-1 | Update the kernel and reboot. DLA-4665-1 shipped the fix on 2026-07-03, in 6.1.176-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.94-1 | Update the kernel and reboot. Fixed in 6.12.94-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.0.13-1 | Update the kernel and reboot. Fixed in 7.0.13-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.13-1 | Update the kernel and reboot. Fixed in 7.0.13-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
When parsing fails after we've matched the command string we should bail out instead of trying to match a different command. This helper should be deprecated, given prevalence of TLS I doubt it has any relevance in 2026.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
net/netfilter/nf_conntrack_irc.c
- What this is
- NETFILTERMAINTAINERS section matched on net/netfilter/ · netfilter-devel@vger.kernel.org · Maintained
- Kernel module
- nf_conntrack_irc
Check it on the machine
grep -wE 'CONFIG_NETFILTER|CONFIG_NF_CONNTRACK_IRC' /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w nf_conntrack_ircPrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this as a loadable module. Every release below compiles it as a module on every flavour, so whether the code is in the running kernel depends on whether that module is loaded.
- bookworm, trixie, forky, sidm
- m
- a loadable module on every flavour - check lsmod, can be blacklisted
- Build switches
- CONFIG_NETFILTER, CONFIG_NF_CONNTRACK_IRC
- Reads as
- all on means the file is compiled; any one off means it is not.
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-06-25 (4 months ago)source
- CVSS
- 8.2 high
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.40%, higher than 32.4% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- net/netfilter
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 2.6.20 | 5.10.259 | 4cdda7f868f4 |
| 2.6.20 | 5.15.210 | 8a1d6e40dedf |
| 2.6.20 | 6.1.176 | 0afc802160af |
| 2.6.20 | 6.6.143 | 7c34f9130529 |
| 2.6.20 | 6.12.94 | ddddd8271359 |
| 2.6.20 | 6.18.36 | 9e5da2379f96 |
| 2.6.20 | 7.0.13 | 573810f61bcd |
| 2.6.20 | 7.1 | 66eba0ffce3b |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4671-1 | 2026-07-05 | bullseye 6.1.176-1~deb11u1 | tracker |
| DLA-4665-1 | 2026-07-03 | bookworm 6.1.176-1 | tracker |
| DLA-4664-1 | 2026-07-03 | bullseye 5.10.259-1 | tracker |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:NAttack vector, network
- The vulnerable IRC conntrack helper parses attacker-controlled TCP payloads on network flows when the helper is attached, such as an IRC-exposed host or firewall/NAT deployment. A remote peer can establish the TCP flow and send the crafted IRC/CTCP DCC text that reaches `help()`.
- AC:LAttack complexity, low
- Once the helper is enabled/assigned, triggering is deterministic packet parsing with attacker-controlled payload bytes and no race or hard-to-shape kernel state. The established-flow requirement is attacker-controlled by completing a normal TCP handshake.
- PR:NPrivileges required, none
- The network attacker does not need local credentials or authenticated IRC privileges to send payload on a tracked TCP connection. Helper configuration requires administrative privileges, but that is deployment state, not attacker privilege.
- UI:NUser interaction, none
- No victim user action is needed after the vulnerable helper is active on the network path. The attacker only sends network traffic.
- S:UScope, unchanged
- The impact is within the kernel/netfilter security authority of the affected system. There is no VM, IOMMU, or separate security-scope boundary crossed.
- C:LConfidentiality impact, low
- This is an out-of-bounds read from the IRC payload buffer/parser state, but the overread is constrained by short command comparisons and parser checks rather than an arbitrary kernel memory read primitive. Under the higher-severity tie-break rule, limited confidentiality impact is appropriate for the possible stale/adjacent-byte exposure.
- I:NIntegrity impact, none
- The bug is a read-side parser bounds error and does not write attacker-controlled data to kernel memory or provide a direct modification primitive. Any conntrack expectation changes require passing the helper's normal DCC validation path and are not arbitrary integrity compromise.
- A:HAvailability impact, high
- The malformed payload can drive `memcmp()`/parser reads beyond the valid copied payload window, and with large/nonlinear packets this can go past the helper's guard byte and plausibly fault/oops in kernel context. The packet can be resent repeatedly for denial of service.