8.2

CVE-2026-63867: linux Race Condition

CVSS: 8.2v3.1HighAwaiting analysis
AliasesUBUNTU-CVE-2026-63867DEBIAN-CVE-2026-63867
Published 19-07-2026Last modified 19-10-2026
Open JSON

Vulnerability summary

CVE-2026-63867 is a high (CVSS 8.2) Race Condition vulnerability in linux. EPSS estimates a 0.34% chance of exploitation in the next 30 days, higher than 25.8% of scored vulnerabilities.

Overall risk
33/100
0100
Medium · default modelHow is this calculated?
CVSS score
8.2/10
010
High · v3.1 (CVE.org)
EPSS score
0.34%
0%100%
Low · -0.25 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 24 · Related 23
MGASA-2026-0312USN-8726-1USN-8726-2USN-8726-3USN-8726-4USN-8727-1

Timeline

  1. 19-07-2026
    PublishedVulnerability first disclosed.
  2. 19-10-2026
    Last modifiedVulnerability information updated.

Description

In the Linux kernel, the following vulnerability has been resolved: mptcp: close TOCTOU race while computing rcv_wnd The MPTCP output path access locklessly the MPTCP-level ack_seq in multiple times, using possibly different values for the data_ack in the DSS option and to compute the announced rcv wnd for the same packet. Refactor the cote to avoid inconsistencies which may confuse the peer. Also ensure that the MPTCP level rcv wnd is updated only when the egress packet actually contains a DSS ack.

CVSS metrics

4 scores · 4 sources · 1 version

EPSS trend

Probability

0.34%

Chance of exploitation in the next 30 days

Percentile

26%

Versus all other CVEs

30-day change

-0.25 pp

From 0.59% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.34%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Ubuntu156 products
  • linux< 5.15.0-198.208 | < 6.8.0-146.146 | < 7.0.0-31.31
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-aws< 5.15.0-1117.124 | < 6.8.0-1066.69 | < 7.0.0-1012.12
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Debian1 product
  • linux< 6.1.176-1 | < 6.12.94-1 | < 7.0.13-1
Linux1 product
  • linux≥ fa3fe2b150316b294f2c662653501273ff25bba8, < 301a33fd590c408a05c5df800e0cc1e6a8a2f8f8 | ≥ fa3fe2b150316b294f2c662653501273ff25bba8, < 68364963e5baf03f16b4420292291f75c8f66497 | ≥ fa3fe2b150316b294f2c662653501273ff25bba8, < 907ac6b1658e0277f979fcdfae2a753b495c1510 | ≥ fa3fe2b150316b294f2c662653501273ff25bba8, < c4f4cf60797974873dbc8e100144682a6f2f861f | ≥ fa3fe2b150316b294f2c662653501273ff25bba8, < 3b8cbba7c0ed31189c89f90be247b8973ffa79ef | ≥ fa3fe2b150316b294f2c662653501273ff25bba8, < 8f4f0a157e8436a05bf8c3670b24dbc258911c43 | ≥ fa3fe2b150316b294f2c662653501273ff25bba8, < 8ab24fdebc369c0dfb90f82c1650b1e66662bb45 | 5.11

3 vendors · 158 products

References

34 links
Show all 34 references