CVE-2025-39990: Linux kernel · bpf: Check the helper function is valid in get_helper_proto
Affects Linux kernelSource CVE Database V5
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
- 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:HExploitation evidence
Disclosed: evidence found.
CVE published 15 Oct 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| 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
- git.kernel.org/stable/c/dfbff47f120e4b0793ca0e0b8660361ccac25a74 (opens in a new tab)
- git.kernel.org/stable/c/3d429cb1278e995e22995ef117fa96d223a67e93 (opens in a new tab)
- git.kernel.org/stable/c/6233715b4b714068d6c831d214a4e8792109875a (opens in a new tab)
- git.kernel.org/stable/c/e4414b01c1cd9887bbde92f946c1ba94e40d6d64 (opens in a new tab)