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CVE-2026-74469
sctp: prevent peer transport count overflow
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem net/sctp. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-74469 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-4777-1 · 2026-09-08 · text | 6.1.187-1 | Update the kernel and reboot. DLA-4777-1 shipped the fix on 2026-09-08, in 6.1.187-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixedDSA-6466-1 · 2026-08-25 · text | 6.12.105-1 | Update the kernel and reboot. DSA-6466-1 shipped the fix on 2026-08-25, in 6.12.105-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.8-1 | Update the kernel and reboot. Fixed in 7.1.8-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.8-1 | Update the kernel and reboot. Fixed in 7.1.8-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4788-1 · 2026-09-19 · text | 6.12.107-1~deb12u1 | Update the kernel and reboot. DLA-4788-1 shipped the fix on 2026-09-19, in 6.12.107-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
sctp_assoc_add_peer() increments the association's 16-bit transport_count for every new unique peer. Adding the 65,536th transport wraps the count to zero. SCTP sock_diag uses transport_count to reserve the INET_DIAG_PEERS payload, then copies one sockaddr_storage for every entry in transport_addr_list. After the wrap, a diagnostic dump reserves an empty payload and writes 8 MiB of peer addresses past the skb tail. Reject a new unique peer when transport_count has reached U16_MAX. Perform the check after the existing-peer lookup so a duplicate address continues to return its existing transport at the limit.
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/sctp/associola.c
- What this is
- SCTP PROTOCOLMAINTAINERS section matched on net/sctp/ · linux-sctp@vger.kernel.org · Maintained
- Kernel module
- sctp
Check it on the machine
grep -w CONFIG_IP_SCTP /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 sctpPrints 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, sid, bookworm · linux-6.12m
- m
- a loadable module on every flavour - check lsmod, can be blacklisted
- Build switch
- CONFIG_IP_SCTP
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
- 2026-08-15 (2 months ago)source
- CVSS
- 8.8 high
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 1.47%, higher than 73.3% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- net/sctp
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 4.7 | 5.10.265 | b453e00da121 |
| 4.7 | 5.15.216 | dfea32dd76f3 |
| 4.7 | 6.1.183 | 80f48523a0fe |
| 4.7 | 6.6.151 | 546221b86cee |
| 4.7 | 6.12.103 | 09e722030e81 |
| 4.7 | 6.18.44 | 4ba5bf7ed50f |
| 4.7 | 7.1.8 | 6201cd1d70f1 |
| 4.7 | 7.2 | bd0e9289e264 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4788-1 | 2026-09-19 | bookworm 6.12.107-1~deb12u1 | tracker |
| DLA-4777-1 | 2026-09-08 | bookworm 6.1.187-1 | tracker |
| DSA-6466-1 | 2026-08-25 | trixie 6.12.105-1 | 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
- Remote SCTP peers add unique transports via INIT address parameters and ASCONF ADD_IP chunks processed in sctp_assoc_add_peer(); this is network ingress on SCTP servers (telecom, signaling gateways) before any local diagnostic action.
- AC:LAttack complexity, low
- An attacker controlling an SCTP association can script 65536 unique peer addresses via connectx, repeated ASCONF ADD_IP, or INIT parameters; no race or victim-specific state is required beyond reaching the transport limit.
- PR:LPrivileges required, low
- The heap overflow is triggered via NETLINK_SOCK_DIAG (ss/netlink), reachable by unprivileged users; SCTP socket creation and connectx need no capabilities beyond a normal local account (including user namespaces).
- UI:NUser interaction, none
- Exploitation requires no victim interaction; the attacker drives transport accumulation and issues the diagnostic dump themselves.
- S:UScope, unchanged
- Impact is kernel heap corruption within the same kernel security boundary; this is not a VM escape, sandbox breakout, or cross-authority scope change.
- C:HConfidentiality impact, high
- When transport_count wraps to zero, inet_diag_msg_sctpaddrs_fill() reserves no space but iterates all 65536 transports, writing ~8 MiB past the skb tail and enabling adjacent kernel heap reads.
- I:HIntegrity impact, high
- The same diag path performs a massive out-of-bounds write of sockaddr_storage entries past the allocated skb buffer, corrupting adjacent kernel heap objects and enabling control-flow hijacking.
- A:HAvailability impact, high
- Corrupting sk_buff heap metadata and adjacent allocations via an ~8 MiB out-of-bounds write can cause kernel oops, panic, or hang, meeting high availability impact.