CVE-2016-4557

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 10.2% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2016-05-23 · updated 2026-06-17

Description

The replace_map_fd_with_map_ptr function in kernel/bpf/verifier.c in the Linux kernel before 4.5.5 does not properly maintain an fd data structure, which allows local users to gain privileges or cause a denial of service (use-after-free) via crafted BPF instructions that reference an incorrect file descriptor.

Affected products

Linux kernel: from 4.4 before 4.4.11; from 4.5 before 4.5.5 — fixed in 4.4.11, 4.5.5

How to fix

Upgrade to a fixed version: Linux kernel 4.4.11, 4.5.5. Check the vendor advisory for mitigations.

References

http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=8358b02bf67d3a5d8a825070e1aa73f25fb2e4c7
http://lists.opensuse.org/opensuse-security-announce/2016-06/msg00044.html
http://www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.5.5
http://www.openwall.com/lists/oss-security/2016/05/06/4
https://bugs.chromium.org/p/project-zero/issues/detail?id=808
https://bugs.debian.org/823603
https://bugzilla.redhat.com/show_bug.cgi?id=1334307
https://github.com/torvalds/linux/commit/8358b02bf67d3a5d8a825070e1aa73f25fb2e4c7
https://www.exploit-db.com/exploits/40759/
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=8358b02bf67d3a5d8a825070e1aa73f25fb2e4c7
http://lists.opensuse.org/opensuse-security-announce/2016-06/msg00044.html
http://www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.5.5

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