CVE-2026-43070: Linux kernel · bpf: Reset register ID for BPF_END value tracking
Source GCVE Database
Not known to be exploited · CVSS 7.8 High.
Data as of 27 Oct 2026, 00:07 UTC
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 5 May 2026
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.
Description
In the Linux kernel, the following vulnerability has been resolved: bpf: Reset register ID for BPF_END value tracking When a register undergoes a BPF_END (byte swap) operation, its scalar value is mutated in-place. If this register previously shared a scalar ID with another register (e.g., after an `r1 = r0` assignment), this tie must be broken. Currently, the verifier misses resetting `dst_reg->id` to 0 for BPF_END. Consequently, if a conditional jump checks the swapped register, the verifier incorrectly propagates the learned bounds to the linked register, leading to false confidence in the linked register's value and potentially allowing out-of-bounds memory accesses. Fix this by explicitly resetting `dst_reg->id` to 0 in the BPF_END case to break the scalar tie, similar to how BPF_NEG handles it via `__mark_reg_known`.
References
- nvd.nist.gov/vuln/detail/CVE-2026-43070 (opens in a new tab)
- git.kernel.org/stable/c/0d15c3611a2cc5d08993545d4032055ae10ae2c1 (opens in a new tab)
- git.kernel.org/stable/c/a17443af874229408ce6b78e2c8a2b5adeb4b7d8 (opens in a new tab)
- git.kernel.org/stable/c/a3125bc01884431d30d731461634c8295b6f0529 (opens in a new tab)