CVE-2026-49457 QUIC has Broken TLS verification
A man-in-the-middle can impersonate servers because the Erlang QUIC client failed to validate TLS certificates, compromising connection confidentiality and integrity.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-49457?
CVE-2026-49457 is a critical vulnerability in benoitc erlang_quic, published on 14 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
erlang_quic is a pure Erlang QUIC implementation. Prior to version 1.4.4, the QUIC client did not authenticate the server during the TLS 1.3 handshake. The CertificateVerify signature was not checked, the certificate chain was not validated, and the hostname was not compared against the certificate, so `verify` was effectively a no-op on the client. A man-in-the-middle on the network path could present any certificate and impersonate any server, defeating the confidentiality and integrity of the connection. HTTP/3 uses the same client and was equally affected. Handshakes authenticated by a PSK (session resumption) are not affected, because the peer is authenticated by the PSK binder and no certificate is sent. This is fixed in 1.4.4. The client now verifies the CertificateVerify signature, validates the certificate chain against the trust store (`cacerts` option, the operating system store by default), and checks the hostname. Client `verify` now defaults to on; set `verify => false` to accept any certificate (for example a self-signed test server). No known workarounds are available before 1.4.4. `verify => true` had no effect, and inspecting the certificate after connecting does not help because without the signature check the peer is never proven to own the certificate it presents.
Which versions are affected by CVE-2026-49457?
2 open source packages ship an affected version, including quic.
| Package | Affected | Fixed in |
|---|---|---|
quic Hex | All versions | 1.4.4 |
quic Hex | All versions | 1.4.4 |
How do I fix CVE-2026-49457?
Upgrade quic to 1.4.4 or later.
Is CVE-2026-49457 being exploited?
There is no known exploitation of CVE-2026-49457 in the wild and no public exploit code.
Sources
Also known as GHSA-2r8v-p65x-3663.