GHSA-3m6q-h5gj-7mrw

Suggest an improvement
Source
https://github.com/advisories/GHSA-3m6q-h5gj-7mrw
Import Source
https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/04/GHSA-3m6q-h5gj-7mrw/GHSA-3m6q-h5gj-7mrw.json
JSON Data
https://api.osv.dev/v1/vulns/GHSA-3m6q-h5gj-7mrw
Aliases
Published
2026-04-22T20:37:21Z
Modified
2026-06-25T18:56:39Z
Severity
  • 6.3 (Medium) CVSS_V4 - CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N CVSS Calculator
Summary
Gitea has insecure default SSH settings
Details

Summary

The built-in SSH server currently advertises a number of key exchange, MAC, and host key algorithms that are considered weak or broken. The defaults should be tightened so a fresh installation passes a baseline SSH security audit out of the box.

Details

Running ssh-audit against a default deployment flags the following as fail:

  • Key exchange
    • ecdh-sha2-nistp256
    • ecdh-sha2-nistp384
    • ecdh-sha2-nistp521
  • MAC
    • hmac-sha1
  • Host key
    • ssh-rsa

Reproduction

docker run -it --rm positronsecurity/ssh-audit -p 2222 gitea.local

Impact

Default deployments expose algorithms that are known-weak or deprecated upstream. The current workaround requires manually setting several GITEA__server__SSH_SERVER_* variables, which most users will never do.

Workaround

[server]
SSH_SERVER_KEY_EXCHANGES = curve25519-sha256, diffie-hellman-group14-sha256
SSH_SERVER_CIPHERS       = chacha20-poly1305@openssh.com, aes128-ctr, aes192-ctr, aes256-ctr, aes128-gcm@openssh.com, aes256-gcm@openssh.com
SSH_SERVER_MACS          = hmac-sha2-256-etm@openssh.com, hmac-sha2-256

There is no exposed option to restrict host key algorithms, so ssh-rsa remains advertised.

Acceptance criteria

  • Default SSH_SERVER_KEY_EXCHANGES, SSH_SERVER_CIPHERS, and SSH_SERVER_MACS updated to the secure list above.
  • New SSH_SERVER_HOST_KEY_ALGORITHMS option added, with a default that excludes ssh-rsa.
  • Documentation updated to reflect the new defaults.
  • ssh-audit against a fresh install reports no [fail] entries.
Database specific 
{
    "cwe_ids":  [
        "CWE-1188",
        "CWE-327"
    ],
    "github_reviewed":  true,
    "github_reviewed_at":  "2026-04-22T20:37:21Z",
    "nvd_published_at":  null,
    "severity":  "MODERATE"
}
References

Affected packages

Go / code.gitea.io/gitea

Package

Name
code.gitea.io/gitea
View open source insights on deps.dev
Purl
pkg:golang/code.gitea.io/gitea

Affected ranges

Type
SEMVER
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
1.25.0

Database specific

source 
"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/04/GHSA-3m6q-h5gj-7mrw/GHSA-3m6q-h5gj-7mrw.json"