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CVE-2025-39702

ipv6: sr: Fix MAC comparison to be constant-time

HIGH
7
CVSS Score
Published: September 5, 2025 at 05:21 PM UTC
Updated: October 19, 2026 at 09:10 PM UTC
3 products affected across 3 vendorsLinux KernelDebian LinuxSIMATIC CN 4100

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Severity
HIGH7
Exploit prediction
EPSS 0.4%
SSVC
No known exploit

Description

In the Linux kernel, the following vulnerability has been resolved: ipv6: sr: Fix MAC comparison to be constant-time To prevent timing attacks, MACs need to be compared in constant time. Use the appropriate helper function for this.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Debian Linux· Debiandrupal
95%
11.0
Linux Kernel· Linux
95%
4.10 ≤ v < 5.15.1905.16 ≤ v < 6.1.1496.13 ≤ v < 6.16.46.2 ≤ v < 6.6.1036.7 ≤ v < 6.12.446.176.17 rc16.17 rc2bf355b8d2c30a289232042cacc1cfaea4923936c
Vendor states this is fixed in 3b348c9c8d2ca2c67559ffd0e258ae7e1107d4f0 (fixed)
Vendor states this is fixed in 3ddd55cf19ed6cc62def5e3af10c2a9df1b861c3 (fixed)
Vendor states this is fixed in 86b6d34717fe0570afce07ee79b8eeb40341f831 (fixed)
Vendor states this is fixed in a458b2902115b26a25d67393b12ddd57d1216aaa (fixed)
Vendor states this is fixed in b3967c493799e63f648e9c7b6cb063aa2aed04e7 (fixed)
Vendor states this is fixed in f7878d47560d61e3f370aca3cebb8f42a55b990a (fixed)
Vendor states this is fixed in ff55a452d56490047f5233cc48c5d933f8586884 (fixed)
Vendor states this is fixed in 4.10 (unaffected)
Vendor states this is fixed in 5.10.249 (unaffected)
Vendor states this is fixed in 5.15.190 (unaffected)
Vendor states this is fixed in 6.1.149 (unaffected)
Vendor states this is fixed in 6.12.44 (unaffected)
Vendor states this is fixed in 6.16.4 (unaffected)
Vendor states this is fixed in 6.17 (unaffected)
Vendor states this is fixed in 6.6.103 (unaffected)
SIMATIC CN 4100· Siemens
60%
v < V5.0
Affected range stops below V5.0, so it looks safe — our inference, not a vendor statement

References (9)

Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/3b348c9c8d2ca2c67559ffd0e258ae7e1107d4f0
Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/3ddd55cf19ed6cc62def5e3af10c2a9df1b861c3
Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/86b6d34717fe0570afce07ee79b8eeb40341f831
Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/a458b2902115b26a25d67393b12ddd57d1216aaa
Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/b3967c493799e63f648e9c7b6cb063aa2aed04e7
Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/f7878d47560d61e3f370aca3cebb8f42a55b990a
Patch
Source: cverecord
https://git.kernel.org/stable/c/ff55a452d56490047f5233cc48c5d933f8586884
Mailing ListThird Party Advisory
Source: af854a3a-2127-422b-91ae-364da2661108
https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html

SSVC — Action Prioritization

SSVCNo known exploitAutomatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7HIGH[email protected]
Attack Vector
LOCAL
Complexity
HIGH
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-203

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