Look up another CVE · open CVE-2026-68300 in the interactive tracker
CVE-2026-68300
sctp: auth: verify auth requirement when auth_chunk is NULL
Published 2026-08-10 (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-2026-68300 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 | fixed | 6.12.101-1 | Update the kernel and reboot. Fixed in 6.12.101-1. A running kernel keeps the old code until the machine restarts. |
| 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. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4745-1 · 2026-08-18 · text | 6.12.101-1~deb12u1 | Update the kernel and reboot. DLA-4745-1 shipped the fix on 2026-08-18, in 6.12.101-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
sctp_auth_chunk_verify() returns true unconditionally when chunk->auth_chunk is NULL, silently skipping authentication. This is incorrect when: 1. skb_clone() failed in the BH receive path, leaving auth_chunk NULL. In sctp_endpoint_bh_rcv() asoc is NULL for new connections, so the early sctp_auth_recv_cid() check cannot catch this. 2. No AUTH chunk precedes COOKIE-ECHO, so skb_clone() is never called and auth_chunk remains NULL. Fix by checking sctp_auth_recv_cid() when auth_chunk is NULL: if authentication is required, return false to drop the chunk; otherwise continue normally.
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/sm_statefuns.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
- 2026-08-10 (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
- 0.59%, higher than 47.1% 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 |
|---|---|---|
| 2.6.24 | 5.10.265 | a129792b3aef |
| 2.6.24 | 5.15.216 | 5a022ac51ad8 |
| 2.6.24 | 6.1.183 | 6caf0e8590c0 |
| 2.6.24 | 6.6.148 | ec2e157fc967 |
| 2.6.24 | 6.12.101 | 28c5fdce9dd9 |
| 2.6.24 | 6.18.42 | 18957373920c |
| 2.6.24 | 7.1.6 | 83f5031f2a6a |
| 2.6.24 | 7.2 | 8e04823c120b |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4777-1 | 2026-09-08 | bookworm 6.1.187-1 | tracker |
| DLA-4745-1 | 2026-08-18 | bookworm 6.12.101-1~deb12u1 | 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 code is SCTP COOKIE-ECHO chunk processing in the kernel's SCTP state machine, reached directly from packets received on the network from any remote peer over an arbitrarily routed SCTP connection.
- AC:LAttack complexity, low
- The attacker deterministically triggers the bypass by completing a normal INIT/INIT-ACK exchange with the AUTH extension advertised and then sending COOKIE-ECHO with no preceding AUTH chunk; no race, no memory-layout dependency, and every step is under the attacker's control.
- PR:NPrivileges required, none
- This is the pre-authentication association-establishment path itself; the attacker needs no credentials, no shared SCTP-AUTH key, and no account, since the bug is precisely that the required authentication is skipped.
- UI:NUser interaction, none
- The listening SCTP endpoint processes the crafted COOKIE-ECHO automatically in the receive path; no action by any local user or administrator is needed.
- S:UScope, unchanged
- The bypass affects the SCTP association and the application relying on it within the same host security authority; no VM, IOMMU, or sandbox boundary is crossed.
- C:HConfidentiality impact, high
- An unauthenticated peer is admitted as an apparently authenticated one, and because peer.auth_capable is set the SCTP_AUTH_NO_AUTH notification is suppressed so the application cannot detect it, giving the attacker full read access to all data the service sends on that association.
- I:HIntegrity impact, high
- The attacker can inject arbitrary SCTP data and control chunks into the service as a trusted, supposedly key-verified peer, and can use the dupcook restart path to update or replace an existing association's state without authentication.
- A:HAvailability impact, high
- Authenticating COOKIE-ECHO is the RFC 4895 defense against unauthorized association restart; bypassing it lets an attacker reset/take over an established association, dropping its queued state and denying service to the legitimate peer, and lets unauthorized peers consume association and accept-queue resources on an endpoint meant to admit only key-holding peers.