Answer in brief
CVE-2026-40611 records a High severity (CVSS 8.8) vulnerability in Lego: Arbitrary File Write via Path Traversal in Webroot HTTP-01 Provider. The current sources do not mark it as known exploited. The current feed maps go-acme/lego (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 8.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps go-acme/lego (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| go-acme/legogeneric | < 4.34.0 | Not reported |
Published upstream
Apr 21, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Jul 15, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jul 15, 2026
Let'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.
Quoted source text, attributed separately from HOL analysis.
Answer in brief
CVE-2026-40611 records a High severity (CVSS 8.8) vulnerability in Lego: Arbitrary File Write via Path Traversal in Webroot HTTP-01 Provider. The current sources do not mark it as known exploited. The current feed maps go-acme/lego (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 8.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps go-acme/lego (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| go-acme/legogeneric | < 4.34.0 | Not reported |
Published upstream
Apr 21, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Jul 15, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jul 15, 2026
Let'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.
Quoted source text, attributed separately from HOL analysis.