CVE-2025-31135 json
Go-Guerrilla SMTP Daemon allows the PROXY command to be sent multiple times
published last yr. modified 4mo ago also GHSA-c2c3-pqw5-5p7c , GO-2025-3588 , EUVD-2025-9432
- cvss
- 5.3
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.4%
- EPSS 0.4% chance of exploitation in 30 days, percentile 32%
- public exploits
- 0
- none known
Summary
Go-Guerrilla SMTP Daemon is a lightweight SMTP server written in Go. Prior to 1.6.7, when ProxyOn is enabled, the PROXY command will be accepted multiple times, with later invocations overriding earlier ones. The proxy protocol only supports one initial PROXY header; anything after that is considered part of the exchange between client and server, so the client is free to send further PROXY commands with whatever data it pleases. go-guerrilla will treat these as coming from the reverse proxy, allowing a client to spoof its IP address. This vulnerability is fixed in 1.6.7.
Patch / fix
- go github.com/phires/go-guerrilla 1.6.7
- govulncheck-vulndb openSUSE Tumbleweed 0.0.20250402T160203-1.1
opensuse advisories openSUSE-SU-2025:14970-1
Is CVE-2025-31135 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerCISA SSVC
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
- Assessed
- last yr.
Exploit prediction
0.38% chance of exploitation in the next 30 days, higher than 32% of all scored CVEs (FIRST EPSS, 2026-11-09).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N |
| GitHub | 3.1 | 5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| go | github.com/phires/go-guerrilla | <1.6.7 |
1.6.7 |
Affected products
- phires go-guerrilla
Classification
- Weakness
-
- CWE-20 Improper Input Validation
References
- github.com /phires/go-guerrilla/commit/d08fe22f8022d2bdedc136f9e4ba96f2fbbebf18
-
github.com
/phires/go-guerrilla/commit/7673947f2d5204a135d7ae0b7f80759e548abee6
web, patch
-
github.com
/phires/go-guerrilla/security/advisories/GHSA-c2c3-pqw5-5p7c
web, advisory
-
nvd.nist.gov
/vuln/detail/CVE-2025-31135
advisory
-
github.com
/phires/go-guerrilla
package
-
pkg.go.dev
/vuln/GO-2025-3588
web
Sources
- CVE List CVE-2025-31135
- GitHub Advisory GHSA-c2c3-pqw5-5p7c
- NVD CVE-2025-31135
- OSV GO-2025-3588
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