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CVE-2026-68379
tcp: fix TIME_WAIT socket reference leak on PSP policy failure
Published 2026-08-10 (2 months ago) by the Linux kernel CNA. Subsystem net/ipv4. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-68379 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 | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | not affected | 6.12.113-1 | Nothing to do. trixie never shipped the vulnerable code. |
| Debian 14forky | fixed | 7.1.6-1 | Update the kernel and reboot. Fixed in 7.1.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.6-1 | Update the kernel and reboot. Fixed in 7.1.6-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
Release the TIME_WAIT socket reference and jump to discard_it upon PSP policy failure in both IPv4 and IPv6 receive paths. This prevents a memory leak of tcp_tw_bucket structures.
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/ipv4/tcp_ipv4.c
net/ipv6/tcp_ipv6.c
- What this is
- NETWORKING [TCP]MAINTAINERS section matched on net/ipv4/tcp*.c · netdev@vger.kernel.org · Maintained
Check it on the machine
grep -w CONFIG_INET /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.
Show whether Debian builds this, per release
Debian builds this code. Every release below compiles the affected file into the kernels it ships.
- bookworm, trixie, forky, sidy
- y
- built into the kernel image on every flavour - only a patch removes it
- Build switch
- CONFIG_INET
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
- 2026-08-10 (2 months ago)source
- CVSS
- 7.5 high
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.60%, higher than 47.7% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- net/ipv4
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.18 | 6.18.42 | e666af5dcc90 |
| 6.18 | 7.1.6 | 374742a961be |
| 6.18 | 7.2 | 2c1931a81122 |
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 leak is triggered entirely by a received TCP segment processed in tcp_v4_rcv()/tcp_v6_rcv() do_time_wait path; a remote peer sending a crafted SYN to a socket in TIME_WAIT reaches the faulty code with no local access.
- AC:LAttack complexity, low
- The attacker fully controls the trigger: send a plain non-PSP-encapsulated SYN with a sequence number above tw_rcv_nxt on the known 4-tuple of a just-closed PSP connection, which deterministically yields TCP_TW_SYN plus a PSP policy failure and leaks the reference every time.
- PR:NPrivileges required, none
- No authentication or privileges are needed; the packet is handled in the TCP input path before any socket-level authorization, and the sender need only be the remote endpoint of a previously established connection.
- UI:NUser interaction, none
- Processing happens in softirq context on packet receive with no involvement from any local user or administrator.
- S:UScope, unchanged
- The leaked tcp_timewait_sock and psp_assoc objects are kernel memory managed by the same security authority as the vulnerable TCP receive path; no privilege or virtualization boundary is crossed.
- C:NConfidentiality impact, none
- The missing inet_twsk_put() only omits a refcount decrement; no memory is read out of bounds, no freed object is accessed, and no data is returned to the attacker.
- I:NIntegrity impact, none
- No kernel data is modified or corrupted; the refcount simply never reaches zero, and refcount_t saturates rather than wrapping, so no use-after-free or write primitive arises.
- A:HAvailability impact, high
- Each triggering packet permanently leaks a tcp_timewait_sock slab object plus its pinned psp_assoc, never reclaimed for the life of the boot; an unauthenticated peer can repeat this across arbitrarily many connections to exhaust kernel memory and drive the system to OOM.