Description
e2guardian v5.4.x <= v5.4.3r is affected by missing SSL certificate validation in the SSL MITM engine. In standalone mode (i.e., acting as a proxy or a transparent proxy), with SSL MITM enabled, e2guardian, if built with OpenSSL v1.1.x, did not validate hostnames in certificates of the web servers that it connected to, and thus was itself vulnerable to MITM attacks.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | e2guardian | 5.3.5-3 | — |
| Debian 13 | e2guardian | 5.3.5-3 | — |
| Debian 12 | e2guardian | 5.3.5-3 | — |
| Debian 10 | e2guardian | 5.3.1-1+deb10u1 | DLA-3564-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | e2guardian | No fix yet | — |
| Ubuntu 26.04 LTS | e2guardian | No fix yet | — |
| Ubuntu 25.10 | e2guardian | No fix yet | — |
| Ubuntu 24.04 LTS | e2guardian | No fix yet | — |
| Ubuntu 22.04 LTS | e2guardian | No fix yet | — |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | e2guardian | No fix yet | — |
| Ubuntu 18.04 LTS | e2guardian | No fix yet | — |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | e2guardian | 5.4.5r-r0 | — |
| Alpine v3.23 | e2guardian | 5.4.5r-r0 | — |
| Alpine v3.22 | e2guardian | 5.4.5r-r0 | — |
| Alpine v3.21 | e2guardian | 5.4.5r-r0 | — |
| Alpine v3.20 | e2guardian | 5.4.5r-r0 | — |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | e2guardian | 5.4.5r-r0 | — |
| Alpine v3.18 | e2guardian | 5.4.5r-r0 | — |
| Alpine v3.17 | e2guardian | 5.4.5r-r0 | — |
| Alpine v3.16 | e2guardian | 5.4.5r-r0 | — |
Advisories 1
- DLA-3564-1 e2guardian - security update Debian Security (DSA / DLA) · Mar 9, 2026
References
- https://github.com/e2guardian/e2guardian/issues/707
- https://github.com/e2guardian/e2guardian/commit/eae46a7e2a57103aadca903c4a24cca94dc502a2
- [oss-security] 20211223 CVE-2021-44273: e2guardian did not validate TLS hostnames mailing-list
- [debian-lts-announce] 20230912 [SECURITY] [DLA 3564-1] e2guardian security update mailing-list