4.5

CVE-2026-121520: Malicious client could set xattr value outside of BuildKit state directory

Received
Published 03-11-2026Last modified 03-11-2026

Vulnerability summary

CVE-2026-121520 is a medium (CVSS 4.5) UNIX Symbolic Link (Symlink) Following vulnerability in moby buildkit. EPSS estimates a 0.14% chance of exploitation in the next 30 days, higher than 3.2% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 4.5, local access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
4.5/10
010
Medium · v4.0 (CVE.org)
EPSS score
0.14%
0%100%
Low · Change unavailable
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Timeline

  1. 03-11-2026
    PublishedVulnerability first disclosed.

Description

In BuildKit versions prior to v0.34.1, a malicious client with access to the BuildKit control APIs can submit a build request that sets an extended attribute on a file outside the BuildKit state directory. Extended attributes in the trusted. or security. namespaces may also be set, potentially giving a program on the host elevated privileges. This issue affects build services that accept build requests from untrusted users. The issue is fixed in v0.34.1.

CVSS metrics

2 scores · 2 sources · 1 version

EPSS trend

Probability

0.14%

Chance of exploitation in the next 30 days

Percentile

3%

Versus all other CVEs

30-day change

Change unavailable

Change unavailable

04-11-202604-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: local access, administrative account, no user interaction (CVSS vector). Other conditions: not stated in public data.

Moby1 product

1 vendor · 1 product

References

1 links