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CVE-2026-52993
tipc: fix double-free in tipc_buf_append()
Published 2026-06-24 (4 months ago) by the Linux kernel CNA. Subsystem net/tipc. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-52993 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 | 7.0.10-1 | Update the kernel and reboot. Fixed in 7.0.10-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.10-1 | Update the kernel and reboot. Fixed in 7.0.10-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
tipc_msg_validate() can potentially reallocate the skb it is validating, freeing the old one. In tipc_buf_append(), it was being called with a pointer to a local variable which was a copy of the caller's skb pointer. If the skb was reallocated and validation subsequently failed, the error handling path would free the original skb pointer, which had already been freed, leading to double-free. Fix this by checking if head now points to a newly allocated reassembled skb. If it does, reassign *headbuf for later freeing operations.
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/tipc/msg.c
- What this is
- TIPC NETWORK LAYERMAINTAINERS section matched on net/tipc/ · netdev@vger.kernel.org · Maintained
- Kernel module
- tipc
Check it on the machine
grep -w CONFIG_TIPC /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 tipcPrints 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 switch
- CONFIG_TIPC
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
- 2026-06-24 (4 months ago)source
- CVSS
- 9.8 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.40%, higher than 33.1% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- net/tipc
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 4.15 | 5.10.258 | a438975a6dcd |
| 4.15 | 5.15.209 | 4ee4deadaae7 |
| 4.15 | 6.1.175 | d3556656c6da |
| 4.15 | 6.6.141 | 0274f24485fc |
| 4.15 | 6.12.91 | 4d104882bc81 |
| 4.15 | 6.18.33 | 1d5e58905588 |
| 4.15 | 7.0.10 | 29940fff1411 |
| 4.15 | 7.1 | d293ca716e7d |
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
- TIPC fragment reassembly is reachable from off-node packets via configured TIPC bearers, including the UDP media path over IP. The most severe reasonable deployment is a TIPC UDP cluster service reachable over a network.
- AC:LAttack complexity, low
- A malicious TIPC peer can craft the fragment sequence to inflate the reassembled skb truesize and make the copied inner message fail validation. No attacker-uncontrolled race or rare condition is required.
- PR:NPrivileges required, none
- No target credentials or local account are required to send TIPC packets to an exposed bearer and establish/use the link path. The checks are TIPC discovery/link state checks, not user authentication.
- UI:NUser interaction, none
- Exploitation is packet-driven and does not require a victim user to open a file, mount anything, or take any other action.
- S:UScope, unchanged
- The bug corrupts kernel networking memory within the same kernel security authority. It does not cross a separate scope such as guest-to-host or an IOMMU boundary.
- C:HConfidentiality impact, high
- The double-free of an skb is kernel heap memory corruption and can be leveraged as a use-after-free primitive. Conservatively, this supports high confidentiality impact.
- I:HIntegrity impact, high
- The double-free/use-after-free condition can be shaped into kernel memory corruption and potential control-flow or data modification primitives. Conservatively, this supports high integrity impact.
- A:HAvailability impact, high
- Even without full exploitation, double-free of a kernel skb can trigger kernel heap corruption, oops, panic, or networking stack crash. This is high availability impact.