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CVE-2025-54799VulnerabilityPublished

CVE-2025-54799: go-acme lego · Cleartext Transmission

Affects go-acme legoSource CVE Database V5

0

Not known to be exploited · CVSS 2.3 Low : upgrade to 4.25.2 when convenient.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 4.0 base score
2.3Low
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 12% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 4.25.2
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 7 Aug 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

What to do

Upgrade go-acme lego to 4.25.2.

Affected software

ProductAffectedFixed in
go-acme legoAffected
  • <4.25.2
Fixed in
  • 4.25.2

AI-suggested

1. Upgrade all instances of the go-acme lego library and CLI to version 4.25.2 or later, where HTTPS enforcement is implemented. 2. Audit and verify all configured ACME server URLs to ensure they use HTTPS exclusively, avoiding any HTTP endpoints. 3. Implement network-level controls such as TLS interception detection and strict transport security policies to prevent downgrade attacks or misconfigurations leading to HTTP usage. 4. Monitor network traffic for any unencrypted ACME protocol communications to detect potential exposure. 5. Educate developers and DevOps teams on the importance of secure ACME client configurations and the risks of using HTTP endpoints. 6. Where possible, restrict lego client usage to trusted internal networks or VPNs to reduce exposure to network attackers. 7. Incorporate automated testing in CI/CD pipelines to detect usage of vulnerable lego versions or insecure URLs.

Description

Let's Encrypt client and ACME library written in Go (Lego). In versions 4.25.1 and below, the github.com/go-acme/lego/v4/acme/api package (thus the lego library and the lego cli as well) don't enforce HTTPS when talking to CAs as an ACME client. Unlike the http-01 challenge which solves an ACME challenge over unencrypted HTTP, the ACME protocol requires HTTPS when a client communicates with the CA to performs ACME functions. However, the library fails to enforce HTTPS both in the original discover URL (configured by the library user) and in the subsequent addresses returned by the CAs in the directory and order objects. If users input HTTP URLs or CAs misconfigure endpoints, protocol operations occur over HTTP instead of HTTPS. This compromises privacy by exposing request/response details like account and request identifiers to network attackers. This was fixed in version 4.25.2.

References

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