Quick answers
- Is CVE-2026-94056 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-94056 being exploited in the wild.
- How severe is CVE-2026-94056?
- High severity, with a CVSS score of 7.5, published 19 September 2026.
- Which products and versions are affected?
- Exim 4.83 to 4.100.
- Is there a fix for CVE-2026-94056?
- A patch was published on 2026-09-18: Version 4.100.1 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-94056 attacked?
- It is attacked over the network, in a hosted service.
- Am I affected by CVE-2026-94056?
- Check whether you run Exim at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
Use of uninitialized data in Proxy Protocol v2 implementation allows a remote attacker to leak up to 230 bytes of stack memory when the configured proxy is buggy or compromised. Attack requires Exim built with Proxy Protocol support and configured to use it. The vulnerability is patched by ensuring complete protocol headers are received before processing.
Affected products
- Exim Exim 4.83 to 4.100
Timeline
- 2026-09-18: disclosed
- 2026-09-18: patched: Version 4.100.1 released