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VulnerabilityPublished Updated

CVE-2025-39990: Linux kernel · bpf: Check the helper function is valid in get_helper_proto

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 7.8 High · fixed in e4414b01c1cd9887bbde92f946c1ba94e40d6d64 : patch Linux kernel soon.

Data as of 26 Oct 2026, 14:18 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 8% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-15.

Patch
Available – fixed in e4414b01c1cd9887bbde92f946c1ba94e40d6d64, dfbff47f120e4b0793ca0e0b8660361ccac25a74, 6233715b4b714068d6c831d214a4e8792109875a +1
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 15 Oct 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade Linux kernel to e4414b01c1cd9887bbde92f946c1ba94e40d6d64, dfbff47f120e4b0793ca0e0b8660361ccac25a74, 6233715b4b714068d6c831d214a4e8792109875a or 3d429cb1278e995e22995ef117fa96d223a67e93.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ f470378c7562a2818b45ed11c98973f2b89eedd3, < e4414b01c1cd9887bbde92f946c1ba94e40d6d64
Fixed in
  • e4414b01c1cd9887bbde92f946c1ba94e40d6d64
LinuxLinuxAffected
  • ≥ f470378c7562a2818b45ed11c98973f2b89eedd3, < dfbff47f120e4b0793ca0e0b8660361ccac25a74
Fixed in
  • dfbff47f120e4b0793ca0e0b8660361ccac25a74
LinuxLinuxAffected
  • ≥ f470378c7562a2818b45ed11c98973f2b89eedd3, < 6233715b4b714068d6c831d214a4e8792109875a
Fixed in
  • 6233715b4b714068d6c831d214a4e8792109875a
LinuxLinuxAffected
  • ≥ f470378c7562a2818b45ed11c98973f2b89eedd3, < 3d429cb1278e995e22995ef117fa96d223a67e93
Fixed in
  • 3d429cb1278e995e22995ef117fa96d223a67e93
LinuxLinuxAffected
  • =5.8
Fixed in–

Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Check the helper function is valid in get_helper_proto kernel test robot reported verifier bug [1] where the helper func pointer could be NULL due to disabled config option. As Alexei suggested we could check on that in get_helper_proto directly. Marking tail_call helper func with BPF_PTR_POISON, because it is unused by design. [1] https://lore.kernel.org/oe-lkp/202507160818.68358831-lkp@intel.com

References

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