Vulnerability Details CVE-2026-31413
In the Linux kernel, the following vulnerability has been resolved:
bpf: Fix unsound scalar forking in maybe_fork_scalars() for BPF_OR
maybe_fork_scalars() is called for both BPF_AND and BPF_OR when the
source operand is a constant. When dst has signed range [-1, 0], it
forks the verifier state: the pushed path gets dst = 0, the current
path gets dst = -1.
For BPF_AND this is correct: 0 & K == 0.
For BPF_OR this is wrong: 0 | K == K, not 0.
The pushed path therefore tracks dst as 0 when the runtime value is K,
producing an exploitable verifier/runtime divergence that allows
out-of-bounds map access.
Fix this by passing env->insn_idx (instead of env->insn_idx + 1) to
push_stack(), so the pushed path re-executes the ALU instruction with
dst = 0 and naturally computes the correct result for any opcode.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.002
EPSS Ranking 13.0%
CVSS Severity
CVSS v3 Score 7.8
References
Products affected by CVE-2026-31413
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cpe:2.3:o:linux:linux_kernel:6.12.75
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cpe:2.3:o:linux:linux_kernel:6.12.77
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cpe:2.3:o:linux:linux_kernel:6.12.78
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cpe:2.3:o:linux:linux_kernel:6.18.16
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cpe:2.3:o:linux:linux_kernel:6.18.17
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cpe:2.3:o:linux:linux_kernel:6.18.18
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cpe:2.3:o:linux:linux_kernel:6.18.19
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cpe:2.3:o:linux:linux_kernel:6.18.20
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cpe:2.3:o:linux:linux_kernel:6.19.10
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cpe:2.3:o:linux:linux_kernel:6.19.6
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cpe:2.3:o:linux:linux_kernel:6.19.7
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cpe:2.3:o:linux:linux_kernel:6.19.8
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cpe:2.3:o:linux:linux_kernel:6.19.9