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


- **Severity:** High 8.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 31 Mar 2026
- **Updated:** 2 Apr 2026
- **Also known as:** BELL-CVE-2026-34040, CLEANSTART-2026-GL76811, CLEANSTART-2026-LO90472, CLEANSTART-2026-RR21163, CLEANSTART-2026-TC24088, CLEANSTART-2026-YI67273, CLEANSTART-2026-YU14908, DEBIAN-CVE-2026-34040, ECHO-65c5-c654-e8d5, GHSA-x744-4wpc-v9h2, GO-2026-4887, MINI-22q3-rh9c-7cjf, MINI-2549-h2f9-r5hh, MINI-25r7-579r-w36r, MINI-25vv-797r-xf2c, MINI-26wf-f8qg-3f4w, MINI-2c8g-xmfp-v2w4, MINI-2h72-m45q-x24c, MINI-2hw2-97jf-88vc, MINI-2p24-mxv8-hqff, MINI-2q4w-r44w-55g8, MINI-2wgg-c5qm-rr63, MINI-2xv3-vr8p-qc25, MINI-34w6-8xx6-qqrc, MINI-3658-3g3p-3c37, MINI-36w2-wr5f-xv6f, MINI-376g-mghh-r95r, MINI-39vg-f4cx-4wjw, MINI-3fj4-h3r6-vf2h, MINI-3fpc-8w77-9fx3, MINI-3grf-qpp4-58vq, MINI-42cf-h642-xcmc, MINI-42jv-7p84-rcjf, MINI-42r8-wv6g-84g3, MINI-43pr-xx2g-g693, MINI-45ww-4rc6-wm55, MINI-46x5-x2c2-6f27, MINI-48h4-63g3-8cc2, MINI-49wg-j732-934q, MINI-4c92-ggpv-gj36, MINI-4cc5-w2hc-wxcv, MINI-4ccw-vvjf-q7c7, MINI-4fh3-2xm8-g876, MINI-4g4f-w94f-w9v4, MINI-4gf5-vjcg-hf5g, 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MINI-7xcf-48j5-9xx4, MINI-8439-g24m-2x3v, MINI-854j-h526-2hwx, MINI-873v-98mq-6fpf, MINI-88v7-cqm8-q5c5, MINI-8cp3-x6gp-rx57, MINI-8gf3-6qq8-mj4q, MINI-8gg7-hcj8-jr62, MINI-8gp3-2j8x-fq4g, MINI-8mjf-r92c-9p33, MINI-8q5g-r94x-4mxh, MINI-9276-qh8j-j3hf, MINI-996j-6wxm-q22c, MINI-996r-hgp7-8g86, MINI-997f-wj3c-rvgp, MINI-99jf-h7v7-vfjv, MINI-99q8-fj7r-w48m, MINI-99vh-357g-h6j6, MINI-9ffv-5c4m-r4hr, MINI-9gx4-hgq8-wjwg, MINI-9h2f-wfw7-hwmj, MINI-9j6p-m7gw-mxvr, MINI-9jqx-8jjr-38wf, MINI-9qp9-jvxj-vjhq, MINI-9vch-gw6f-24cm, MINI-9vhh-3xvh-mj2h, MINI-9w53-qqqf-x665, MINI-9x77-494r-xmj8, MINI-9xqj-v9rc-q6xv, MINI-c228-438m-4375, MINI-c3qq-5jp2-q5m7, MINI-c45w-r6wx-9q69, MINI-c4mw-fg89-p234, MINI-c558-46fm-vhff, MINI-c6qg-mv33-3x3x, MINI-c9mj-xhw6-6j4q, MINI-ccc5-xh5m-ffx8, MINI-cccv-5h6c-7hwh, MINI-cf9g-jr9v-9f8x, MINI-cgc3-xrpc-9vjg, MINI-cjw4-gwc3-7v86, MINI-f2mm-x9v8-j3h8, MINI-f437-v7c2-5jr9, MINI-f5gm-q5g4-r56v, MINI-f67q-xrfv-xvf8, MINI-f6m8-qr3x-rj63, MINI-f754-gx7f-qxhx, MINI-f92w-jrqj-j374, MINI-f9pw-m22p-w64c, MINI-ffm2-5fwh-994q, MINI-fmp9-vpw6-vj9w, MINI-fp2v-fjpj-7gc6, MINI-fp57-f27g-74rr, MINI-fqv3-9h58-x372, MINI-fv3m-cwhv-45hx, MINI-fv3q-5882-3qj5, MINI-fvpc-gcqp-g5jj, MINI-g8vj-q5vm-223h, MINI-gc3c-7vh8-ww2c, MINI-gc69-jfh7-2j3x, MINI-gf9p-mm73-565f, MINI-ghg7-5q88-657v, MINI-gm7w-j52h-7424, MINI-gpfv-9g2w-hxhp, MINI-gvjf-vf5v-xj4m, MINI-gx6f-mpmj-6rrm, MINI-gxhf-93px-rf69, MINI-h5r2-p289-jm9j, MINI-h5x7-4g6g-8m24, MINI-h745-jrqr-hvjf, MINI-h8q6-q4q8-x649, MINI-hcvc-ch27-56ff, MINI-hgjh-47hp-6q46, MINI-hgvp-h9h4-8wcj, MINI-hgw2-c393-rmjw, MINI-hj8x-cjp9-x2hp, MINI-hr7r-998c-mfjq, MINI-hvwr-f5vj-5hh9, MINI-hx9g-7rfp-mf2m, MINI-j288-rwqr-h3v7, MINI-j377-x5xr-cf7m, MINI-j39p-h3xj-pp4c, MINI-j48j-wmqm-93gw, MINI-jfcj-x3rg-7v96, MINI-jggv-9v2g-9mw8, MINI-jhfx-cffg-w8f2, MINI-jjg4-2gqx-2x3v, MINI-jmh9-6r95-rhgx, MINI-jrh5-5v3h-q39v, MINI-jx72-75rj-cfc4, MINI-jx7w-f88w-92w2, MINI-jxr9-xr7h-r972, MINI-m53x-ww9p-fmc6, MINI-m5p6-h2rr-4h3v, MINI-m795-x8j9-mj2g, MINI-mf98-xfvq-rc55, MINI-mq7q-mcj6-cqc3, MINI-mrv9-99r2-phg4, MINI-mv2g-p682-mx6q, MINI-mvcv-xrjv-m756, MINI-mvg5-qhrq-3qjh, MINI-mvrj-39q8-gmq3, MINI-p25q-5848-99m3, MINI-p2g7-fhpr-rgmj, MINI-p3m4-vqv8-qqw7, MINI-p4c9-p679-w42v, MINI-p6pm-7gm8-hjxc, MINI-p7qm-674m-rjch, MINI-p7r6-9hch-vr8x, MINI-p8w5-ch2m-9q2f, MINI-p959-hcpj-x8wx, MINI-pf9m-w6hg-9m75, MINI-pg67-wwq6-3cqf, MINI-pgjq-3r28-fxq8, MINI-pj75-xf4m-92v9, MINI-pjq3-22v4-247r, MINI-pmmw-chxx-vcgq, MINI-pvhg-5w95-jmrx, MINI-pvpv-3xq6-45cw, MINI-pvqp-wmrc-86x7, MINI-px45-xxhx-3hq8, MINI-pxr5-9j33-q5jw, MINI-pxrx-hm6g-5qxg, MINI-q8qc-xj6p-7qqw, MINI-q9fg-56gq-fh37, MINI-qc2h-2hmr-fpv2, MINI-qjjv-qwwg-wq6m, MINI-qm88-cwg9-68vf, MINI-qx33-rprj-6w6g, MINI-qx8w-6frj-85v3, MINI-qxcg-cqg9-jgrx, MINI-r227-28ch-56qv, MINI-r2g4-r6f8-f5fc, MINI-r2mp-6744-jmvh, MINI-r553-7wc7-3xrj, MINI-r5h9-6vj9-m4p8, MINI-r626-m5q6-r3j8, MINI-r6gp-xhq9-vrqw, MINI-r74c-f3w2-r36r, MINI-r843-whhf-78fc, MINI-rc7c-f928-895p, MINI-rf68-crmf-9j9x, MINI-rg73-6f5r-q69h, MINI-rg7c-4j65-xfcw, MINI-rg7m-h267-6g9q, MINI-rj3f-r8ff-3vj2, MINI-rrc2-3vm2-836j, MINI-rvpv-wxr8-gh98, MINI-rwq7-42gh-mg7x, MINI-v2gx-r8gf-g2c2, MINI-v59g-gm7c-4g5g, MINI-vcm7-fx9w-fwgw, MINI-vgwm-cv9w-vj2j, MINI-vmpm-h888-7qph, MINI-vp5x-8gvq-phpf, MINI-vpjp-xw7q-3j4f, MINI-vqx9-cjr2-72rq, MINI-vv4m-hvg8-5rrq, MINI-w25r-5g59-4rwq, MINI-w2jv-49hm-f438, MINI-w7xp-6jw3-wgw4, MINI-w83r-vrhj-q7c9, MINI-wc88-49pc-9p7v, MINI-wc8q-gq83-x84c, MINI-wjcf-822m-pm3v, MINI-wq5w-mrxh-2xjm, MINI-wrm3-mxhm-wm53, MINI-wrx8-r384-mj47, MINI-wwhw-gmxg-47x9, MINI-x22m-rgv4-p4c4, MINI-x23q-fxhm-6m85, MINI-x4h8-rxrm-mpcq, MINI-x5xj-h5x5-8rq4, MINI-x7cc-5xwv-828g, MINI-x823-pq3v-2rpm, MINI-x85v-3w4j-6jmx, MINI-x87f-9597-gjx6, MINI-x8mj-xvvf-8mvp, MINI-xfw3-x3jq-gw97, MINI-xg9w-xr93-m37g, MINI-xqg7-rgxg-ff4v, MINI-xqp7-5ccv-rvx5, OESA-2026-1888, ROOT-APP-GOBINARY-CVE-2026-34040, UBUNTU-CVE-2026-34040

## What is CVE-2026-34040?

CVE-2026-34040 is a high-severity vulnerability in moby, published on 31 Mar 2026. 

### Official description

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.

Weakness: CWE-288 (Authentication Bypass Using an Alternate Path or Channel)

## Which versions are affected by CVE-2026-34040?

7 open source packages ship an affected version, including github.com/moby/moby, github.com/docker/docker and github.com/moby/moby/v2. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/moby/moby` | Go | All versions | None |
| `github.com/moby/moby` | Go | All versions | 29.3.1 |
| `github.com/moby/moby` | Go | All versions | 29.3.1 |
| `github.com/docker/docker` | Go | All versions | None |
| `github.com/moby/moby/v2` | Go | All versions | 2.0.0-beta.8 |
| `github.com/moby/moby/v2` | Go | All versions | 2.0.0-beta.8 |
| `github.com/moby/moby/v2` | Go | All versions | 2.0.0-beta.8 |

Products: Docker Engine.

## How do I fix CVE-2026-34040?

Upgrade github.com/moby/moby to 29.3.1 or later.

## Is CVE-2026-34040 being exploited?

There is no known exploitation of CVE-2026-34040 in the wild and no public exploit code.

Public exploit code:

- https://github.com/m0nk3ygod/CVE-2026-34040-PoC (github_poc): https://github.com/m0nk3ygod/CVE-2026-34040-PoC

## Other vulnerabilities in moby

- [CVE-2026-42306](https://insights.sbomify.com/CVE-2026-42306/): Moby: Race condition in docker cp allows bind mount redirection to host path (high 7.2)
- [CVE-2026-33997](https://insights.sbomify.com/CVE-2026-33997/): Moby: Off-by-one error in plugin privilege validation (medium 6.8)
- [CVE-2026-41568](https://insights.sbomify.com/CVE-2026-41568/): Moby: Race condition in docker cp allows creation of arbitrary empty files on the host via symlink swap (medium 6.1)
- [CVE-2018-20699](https://insights.sbomify.com/CVE-2018-20699/): Denial of service in n/a (medium 4.9)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-34040 and fix it if it is affected.

What it is: CVE-2026-34040 is a high-severity vulnerability in moby, published on 31 Mar 2026. 
Exploitation: There is no known exploitation of CVE-2026-34040 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/moby/moby (Go): affected all versions; no fix listed
- github.com/moby/moby (Go): affected all versions; fixed in 29.3.1
- github.com/moby/moby (Go): affected all versions; fixed in 29.3.1
- github.com/docker/docker (Go): affected all versions; no fix listed
- github.com/moby/moby/v2 (Go): affected all versions; fixed in 2.0.0-beta.8
- github.com/moby/moby/v2 (Go): affected all versions; fixed in 2.0.0-beta.8
- github.com/moby/moby/v2 (Go): affected all versions; fixed in 2.0.0-beta.8

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-34040/ (Markdown: https://insights.sbomify.com/CVE-2026-34040/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-34040
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-34040
- OSV: https://osv.dev/vulnerability/CVE-2026-34040

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-34040/
Summaries are generated and may contain mistakes; the official description above is the record.