CVE-2026-34040 | Moby: AuthZ plugin bypass with oversized request body

Moby is an open source container framework. Prior to version 29.3.1, a security vulnerability has been detected that allows attackers to bypass authorization plugins (AuthZ). This issue has been patched in version 29.3.1.

Published: 2026-03-31 Last update: 2026-04-03 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-34040 is rated Low Risk (35.8/100): CVSS High severity, with low exploitation likelihood (EPSS 0.01%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-34040

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-03-31 — 0.01% —

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-34040

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.8 3.1 HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.0 6.0 [email protected]
7.8 3.1 HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.8 5.9 [email protected]

Weakness enumeration for CVE-2026-34040

GitHub Security Advisory for CVE-2026-34040

GHSA-x744-4wpc-v9h2 · Severity: high · Ecosystem: go — Moby has AuthZ plugin bypass when provided oversized request bodies

OS Trackers for CVE-2026-34040

vendor priority summary link
alpine — CVE-2026-34040: 1 source package rows (docker); 1 state rows across 1 repos (edge-community); fixed 1, open 0. https://security.alpinelinux.org/vuln/CVE-2026-34040
debian not yet assigned CVE-2026-34040 not yet assigned priority: Debian including 1 source packages (docker.io), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 3, resolved 2. https://security-tracker.debian.org/tracker/CVE-2026-34040
redhat medium — https://access.redhat.com/security/cve/CVE-2026-34040
suse high — https://www.suse.com/security/cve/CVE-2026-34040/
ubuntu medium CVE-2026-34040 medium priority: Ubuntu including 2 source packages (docker.io, docker.io-app), 12 status rows across 7 suites (bionic, focal, jammy, noble, questing, upstream, xenial): needs-triage 12. https://ubuntu.com/security/CVE-2026-34040

Affected software / configurations for CVE-2026-34040

Vendor Product Version Raw CPE
mobyproject moby < 29.3.1 cpe:2.3:a:mobyproject:moby:*:*:*:*:*:*:*:*

References for CVE-2026-34040

cvelogic Threat Intelligence