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🛡️ CVE-2024-49861 — kernel

🟠 CVSS 7.8 — High ✅ No Known Exploit NVD
7.8
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

bpf: Fix helper writes to read-only maps

In the Linux kernel, the following vulnerability has been resolved:

bpf: Fix helper writes to read-only maps

Lonial found an issue that despite user- and BPF-side frozen BPF map

(like in case of .rodata), it was still possible to write into it from

a BPF program side through specific helpers having ARG_PTR_TO_{LONG,INT}

as arguments.

In check_func_arg() when the argument is as mentioned, the meta->raw_mode

is never set. Later, check_helper_mem_access(), under the case of

PTR_TO_MAP_VALUE as register base type, it assumes BPF_READ for the

subsequent call to check_map_access_type() and given the BPF map is

read-only it succeeds.

The helpers really need to be annotated as ARG_PTR_TO_{LONG,INT} | MEM_UNINIT

when results are written into them as opposed to read out of them. The

latter indicates that it's okay to pass a pointer to uninitialized memory

as the memory is written to anyway.

However, ARG_PTR_TO_{LONG,INT} is a special case of ARG_PTR_TO_FIXED_SIZE_MEM

just with additional alignment requirement. So it is better to just get

rid of the ARG_PTR_TO_{LONG,INT} special cases altogether and reuse the

fixed size memory types. For this, add MEM_ALIGNED to additionally ensure

alignment given these helpers write directly into the args via *<ptr> = val.

The .arg*_size has been initialized reflecting the actual sizeof(*<ptr>).

MEM_ALIGNED can only be used in combination with MEM_FIXED_SIZE annotated

argument types, since in !MEM_FIXED_SIZE cases the verifier does not know

the buffer size a priori and therefore cannot blindly write *<ptr> = val.

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability high.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

  • Attack vector: Local — a local account, shell or session on the host is needed.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: Low — an ordinary user account is enough.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: High — total loss, or loss the attacker controls.
  • Integrity impact: High — total loss, or loss the attacker controls.
  • Availability impact: High — total loss, or loss the attacker controls.

Affected software

CVE-2024-49861 is recorded against 2 packages.

  • kernel (from 6.11.0 up to 6.11.2)
  • linux-kernel (from 6.11 up to 6.11.2)

Timeline and source

Published on 21 October 2024 and last revised on 12 August 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from NVD.

References

git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
lists.debian.org (Web)
github.com (Advisory)
nvd.nist.gov (Advisory)
git.kernel.org (Package)

Other advisories for this package

kernel has other advisories on record. If you are patching this one, these are worth checking on the same host:

Details

Severity High
CVSS Score 7.8
CVSS Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE N/A
Public Exploit ✅ No
Source NVD
Published 2024-10-21
Updated 2026-08-20
Modified 2026-08-12

Affected Packages

Software From version Fixed in
kernel 6.11.0 6.11.2
linux-kernel 6.11 6.11.2

Similar Threats

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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