# CVE-2026-61801: github.com/moby/sys/user has a possible DoS via unbounded parsing of user and group database files > An attacker can cause a denial of service via excessive memory consumption by supplying a crafted user or group database file to the moby/sys/user Go library. - **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Any signed-in user - **Attackable:** Local or same network only - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 8 Oct 2026 - **Updated:** 8 Oct 2026 - **Also known as:** AZL-107042, AZL-107072, AZL-107099, AZL-107111, AZL-107243, AZL-107261, AZL-107303, AZL-107336, AZL-107360, AZL-107550, AZL-107571, AZL-107648, AZL-107664, AZL-107691, AZL-107745, AZL-107862, AZL-107883, AZL-107916, CLEANSTART-2026-DC31578, CLEANSTART-2026-VR97754, DEBIAN-CVE-2026-61801, ECHO-a53d-336f-d1fb, GHSA-mjcv-p78q-w5fw, GO-2026-6686, MINI-22wr-c22j-3fm5, MINI-23hr-cg24-qcwg, MINI-24rv-pw43-r628, MINI-2f73-j3r9-9682, MINI-2jmr-p98p-fx8x, MINI-2x6j-p5hm-95qq, MINI-328p-5574-q27f, MINI-3g9r-jm29-p834, MINI-3gff-jw9m-cgxw, MINI-3j98-jpcx-7x89, MINI-3p83-7g55-rf56, MINI-3xf5-vg42-fjqf, MINI-42gr-5vgf-7g3h, MINI-44p9-jcjx-wrh8, MINI-45j3-j6mg-p69m, MINI-4hcv-8h4h-3gcg, MINI-55fj-q384-j6wp, MINI-5mr3-xvcg-xg52, MINI-5r7v-p852-p4w7, MINI-5w9w-rh5r-c8w5, MINI-64f3-7c8g-w2g7, MINI-6f8r-34f4-j4p3, MINI-6fj7-78x4-ppr2, MINI-6hmx-xjvq-cjh9, MINI-6q76-5r6g-pgg5, MINI-7527-fg43-f4pf, MINI-77j7-hhj4-7xq5, MINI-7cmv-x5mh-8m57, MINI-7hf4-mjqw-438f, MINI-7j93-j9r9-cv85, MINI-7m9r-xqvx-rqv9, MINI-7qhx-m4rq-5r62, MINI-7rp9-887m-vgg3, MINI-822v-fw3r-6p4v, MINI-826h-p47f-35g9, MINI-8648-9m28-33rg, MINI-873q-cq38-7w6f, MINI-89w3-4f75-p6jq, MINI-8gp3-2m68-q53x, MINI-8hrg-659m-r972, MINI-8p97-7hrr-8r45, MINI-8pj9-46g5-g6cf, MINI-8pqp-25qq-vw66, MINI-8q96-x553-hp22, MINI-8x5f-m77g-m374, MINI-93rh-vr3p-qfhw, MINI-9j47-cmg5-77r5, MINI-9mh6-g79r-pcq2, MINI-9rj9-8vf5-r49f, MINI-9v93-7qrw-7r55, MINI-c4gf-235r-69xr, MINI-c5hr-p6gc-8732, MINI-c5xc-j6jp-88xr, MINI-cg66-276g-w6cp, MINI-cq87-jc2p-xf42, MINI-cqj3-xqq5-ph5v, MINI-cwqh-hx85-j27v, MINI-f577-jm2v-fpj2, MINI-f6qx-432x-rwjv, MINI-fcfp-p7fg-75hv, MINI-ffhq-xp3f-rvj8, MINI-fgr2-m3fj-mmrg, MINI-fh56-586g-vqj2, MINI-fhjv-45xf-444f, MINI-fp4c-c42c-2p56, MINI-fpmq-vr36-2qw3, MINI-g3mg-8v34-4qpc, MINI-g426-pf49-gqjm, MINI-g5v7-8v27-q9qx, MINI-g6mc-v67j-c233, MINI-g7x8-v57m-5j84, MINI-gm4c-xx2w-8wxr, MINI-gq2g-rr6g-gjwv, MINI-gqp2-c5qm-943q, MINI-gv25-6m2v-7f2w, MINI-gx65-rhp5-25xc, MINI-h499-m785-hf3m, MINI-h6q4-6x96-v3g4, MINI-hc66-66gh-4w5g, MINI-hh4v-gffh-r64j, MINI-hj3r-xv77-9xjg, MINI-hrj4-8mpg-x85q, MINI-j68f-3mm7-53fx, MINI-j9m9-jvv6-rqj6, MINI-jjc4-g552-4ppc, MINI-jmm8-ppqq-4rh8, MINI-jrfj-6vp6-7qj3, MINI-m58q-rfqf-x35v, MINI-m9m6-8jgm-92wf, MINI-mgrj-56cp-hq94, MINI-mphf-x8c8-pqwp, MINI-mrhf-v23h-xwg5, MINI-p2gg-m3c5-w7pr, MINI-p35q-pjxp-cjmq, MINI-p46q-fj8x-9555, MINI-p7g2-gvj3-88g8, MINI-p7gj-9qv6-xmm9, MINI-p95j-rrpv-r3qf, MINI-pf3j-8vhc-p57p, MINI-pqxc-hg8p-9cx4, MINI-pv6w-6f89-gp9w, MINI-q4mj-qwvj-vc9m, MINI-q5gj-hqgg-92fv, MINI-q945-7qfw-87qp, MINI-qvwx-x3w6-m65v, MINI-r389-2whw-8f8g, MINI-r77x-3gxr-92q9, MINI-rm2f-fvxc-gxc7, MINI-rm7q-g759-xch3, MINI-rmmf-h2pw-5524, MINI-rrxr-823h-qrh4, MINI-rw6p-r689-w3xw, MINI-v239-3wj4-p9jf, MINI-v67w-g9fc-9r8g, MINI-v6q4-q6xq-cv4c, MINI-v7j8-465r-c3g3, MINI-vfhh-322c-c8mg, MINI-vfpc-3jr2-4r6w, MINI-vmv6-x329-g928, MINI-vq4f-2wp5-j23g, MINI-vw54-8c25-pff2, MINI-wg8x-5p7c-64mj, MINI-whcw-7hfw-jxfv, MINI-wrh4-48cx-h8g2, MINI-wrrh-vqch-vgfq, MINI-x46x-v9w2-wfh6, MINI-x5f2-gjv9-5259, MINI-x8rw-3572-3jf2, MINI-xgfx-4748-hqhf, MINI-xhcj-rqrw-5fxg, MINI-xjf4-xxrw-x75r, UBUNTU-CVE-2026-61801 ## What is CVE-2026-61801? CVE-2026-61801 is a medium-severity denial of service vulnerability in moby sys, published on 8 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim. ### Official description The `github.com/moby/sys/user` package provides Go utilities for parsing and looking up entries in Unix-style user and group database files. Versions before 0.4.1 do not sufficiently limit entries when parsing `/etc/passwd`- or `/etc/group`-style files, allowing an attacker who can supply a specially crafted file to cause excessive memory consumption and potentially terminate the affected process due to an out-of-memory condition. This issue is patched in version 0.4.1. As a workaround, avoid parsing attacker-controlled user or group database files, or validate and limit untrusted input before parsing it. Weakness: CWE-400 (Uncontrolled Resource Consumption) ## Which versions are affected by CVE-2026-61801? 3 open source packages ship an affected version, including github.com/moby/sys/user. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `github.com/moby/sys/user` | Go | All versions | 0.4.1 | | `github.com/moby/sys/user` | Go | All versions | 0.4.1 | | `github.com/moby/sys/user` | Go | All versions | 0.4.1 | ## How do I fix CVE-2026-61801? Upgrade github.com/moby/sys/user to 0.4.1 or later. ## Is CVE-2026-61801 being exploited? There is no known exploitation of CVE-2026-61801 in the wild and no public exploit code. ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-61801 and fix it if it is affected. What it is: CVE-2026-61801 is a medium-severity denial of service vulnerability in moby sys, published on 8 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim. Exploitation: There is no known exploitation of CVE-2026-61801 in the wild and no public exploit code. Affected packages and fixed versions: - github.com/moby/sys/user (Go): affected all versions; fixed in 0.4.1 - github.com/moby/sys/user (Go): affected all versions; fixed in 0.4.1 - github.com/moby/sys/user (Go): affected all versions; fixed in 0.4.1 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-2026-61801/ (Markdown: https://insights.sbomify.com/CVE-2026-61801/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-61801 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-61801 - OSV: https://osv.dev/vulnerability/CVE-2026-61801 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-61801/ Summaries are generated and may contain mistakes; the official description above is the record.