Look up another CVE · open CVE-2026-74752 in the interactive tracker
CVE-2026-74752
sctp: validate cookie AUTH state before use
Published 2026-08-26 (2 months ago) by the Linux kernel CNA. Subsystem include/net. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-74752 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 | vulnerable | 6.1.190-1 | No fix published anywhere yet, neither in Debian nor upstream for the series bookworm tracks. Watch the Debian tracker page for this CVE. Advisories for bookworm have historically landed a median of 23 days after publication. |
| Debian 13trixie | vulnerable | 6.12.113-1 | No fix published anywhere yet, neither in Debian nor upstream for the series trixie tracks. Watch the Debian tracker page for this CVE. Advisories for trixie have historically landed a median of 11 days after publication. |
| Debian 14forky | fixed | 7.1.10-1 | Update the kernel and reboot. Fixed in 7.1.10-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.10-1 | Update the kernel and reboot. Fixed in 7.1.10-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
When cookie authentication is disabled, COOKIE_ECHO restores fixed-size AUTH fields directly from peer-controlled cookie bytes. A forged RANDOM length, HMAC list, or CHUNKS list can then reach association consumers with lengths or identifiers that were never validated against the local backing arrays. A forged RANDOM length can cause out-of-bounds reads during key-vector construction. A forged HMAC identifier also caused a 32-byte write past a zero-length AUTH chunk, providing a primitive for a local privilege escalation chain. Validate the cookie's RANDOM, HMACS, and CHUNKS parameters at the cookie trust boundary before copying them into the association. Reject invalid types, malformed lengths, unsupported HMAC identifiers, HMAC lists without SHA1, and forbidden chunk ids.
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.
include/net/sctp/auth.h
net/sctp/auth.c
net/sctp/sm_make_chunk.c
- What this is
- SCTP PROTOCOLMAINTAINERS section matched on include/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, sidm
- 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
- 2026-08-26 (2 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
- 0.43%, higher than 36.3% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- include/net
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 2.6.24 | 7.1.10 | 88619b117be1 |
| 2.6.24 | 7.2 | 3dbb44d88b1e |
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 bug is reached when a remote peer sends SCTP COOKIE-ECHO to a listening endpoint; packets enter sctp_rcv() and are handled in sctp_sf_do_5_1D_ce()/sctp_unpack_cookie() with no local syscall required on the victim.
- AC:LAttack complexity, low
- With SCTP-AUTH enabled and cookie_hmac_alg=none, an attacker completes INIT/INIT-ACK, forges peer-controlled AUTH fields in the returned cookie, and reliably triggers sctp_auth_make_key_vector()/sctp_auth_calculate_hmac() via COOKIE-ECHO without races or uncontrollable conditions.
- PR:NPrivileges required, none
- Exploitation is pre-authentication SCTP handshake processing on a listening server; the attacker only needs network reachability to the SCTP port and does not need local account privileges, capabilities, or init-namespace root on the target host.
- UI:NUser interaction, none
- No victim user action is required beyond normal SCTP listener operation; exploitation is achieved solely by sending attacker-crafted COOKIE-ECHO packets over the network during association setup or restart.
- S:UScope, unchanged
- The vulnerability corrupts kernel memory inside the SCTP stack on the target host and enables kernel privilege escalation; it does not cross a separate security boundary such as guest-to-host VM escape or IOMMU/DMA isolation bypass.
- C:HConfidentiality impact, high
- A forged RANDOM length copied from an unauthenticated cookie drives sctp_auth_make_key_vector() to memcpy() beyond the fixed auth_random backing array, enabling out-of-bounds kernel memory reads during association shared-key construction.
- I:HIntegrity impact, high
- Forged HMAC identifiers from the cookie can yield a zero-length AUTH chunk while sctp_auth_calculate_hmac() still writes a 32-byte digest past the allocation, providing a heap overflow primitive the fix commit notes can chain to local privilege escalation.
- A:HAvailability impact, high
- Out-of-bounds reads and the 32-byte heap overflow during COOKIE-ECHO processing can trigger kernel faults, oops, or panic on SCTP servers, and malformed AUTH state can repeatedly crash association input handling.