CVE-2026-40611

NameCVE-2026-40611
DescriptionLet's Encrypt client and ACME library written in Go (Lego). Prior to 4.34.0, the webroot HTTP-01 challenge provider in lego is vulnerable to arbitrary file write and deletion via path traversal. A malicious ACME server can supply a crafted challenge token containing ../ sequences, causing lego to write attacker-influenced content to any path writable by the lego process. This vulnerability is fixed in 4.34.0.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs1134643

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
golang-github-xenolf-lego (PTS)bullseye3.2.0-3.1vulnerable
bookworm4.9.1-1vulnerable
trixie4.9.1-2vulnerable
forky, sid4.9.1-4vulnerable

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
golang-github-xenolf-legosource(unstable)(unfixed)1134643

Notes

https://github.com/go-acme/lego/security/advisories/GHSA-qqx8-2xmm-jrv8

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