What is CVE-2021-47607?

CVE-2021-47607 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10, affecting Linux kernel versions from 5.12 onward and patched in 5.15.11 and 5.16. CVE-2021-47607 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2021-47607?

CVE-2021-47607 has a CVSS score of 5.5 out of 10, rated Medium severity. The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N.

Is there a patch available for CVE-2021-47607?

Yes, CVE-2021-47607 has been patched. Fixed versions include 5.15.11 and 5.16. If you are running Linux kernel 5.12 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2021-47607 actively exploited?

CVE-2021-47607 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2021-47607

Medium

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix kernel address leakage in atomic cmpxchg's r0 aux reg The implementation of BPF_CMPXCHG on a high level has the following parameters: .-[old-val] .-[new-val] BPF_R0 = cmpxchg{32,64}(DST_REG + insn->off, BPF_R0, SRC_REG) `-[mem-loc] `-[old-val] Given a BPF insn can only have two registers (dst, src), the R0 is fixed and used as an auxilliary register for input (old value) as well as output (returning old value from memory location). While the verifier performs a number of safety checks, it misses to reject unprivileged programs where R0 contains a pointer as old value. Through brute-forcing it takes about ~16sec on my machine to leak a kernel pointer with BPF_CMPXCHG. The PoC is basically probing for kernel addresses by storing the guessed address into the map slot as a scalar, and using the map value pointer as R0 while SRC_REG has a canary value to detect a matching address. Fix it by checking R0 for pointers, and reject if that's the case for unprivileged programs.

Package Linux Kernel

Published 2024-06-19

Last modified 2024-11-21

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

5.5

out of 10

Medium

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

None

Vector string

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Affected versions

Linux kernel versions 5.12 and later are affected. Fixed in 5.15.11, 5.16 and their respective stable series.

Affected from

≥ 5.12

Fixed in

✓ 5.15.11 5.15.x ✓ 5.16

References

2 total

Kernel Git
https://git.kernel.org/stable/c/a82fe085f344ef20b452cd5f481010ff96b5c4cd

Patch
Kernel Git
https://git.kernel.org/stable/c/f87a6c160ecc8c7b417d25f508d3f076fe346136

Patch

Details

CVE ID CVE-2021-47607

Severity Medium

CVSS score 5.5 / 10

CVSS version 3.1

Published 2024-06-19

Modified 2024-11-21

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2021-47607?

CVE-2021-47607 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 . It affects Linux kernel versions from 5.12 onward and has been patched in 5.15.11 and 5.16. CVE-2021-47607 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2021-47607?

CVE-2021-47607 has a CVSS score of 5.5 out of 10, rated Medium severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N.
Is there a patch available for CVE-2021-47607?

Yes. CVE-2021-47607 has been patched. Fixed versions include 5.15.11 and 5.16. If you are running Linux kernel 5.12 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2021-47607 actively exploited?

No. CVE-2021-47607 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.