As a catastrophic security flaw, CVE-2026-49457 has severe implications, demanding immediate intervention.
Status: Received on 14 Aug 2026, 19:17 UTC
Published on: 14 Aug 2026, 19:17 UTC
CVSS Release: version 3
security-advisories@github.com
Secondary
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CVE-2026-49457: 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.
The exploitability of CVE-2026-49457 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).
With low attack complexity and no required privileges, CVE-2026-49457 is an easy target for cybercriminals. Organizations should prioritize immediate mitigation measures to prevent unauthorized access and data breaches.
A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.
Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.
Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.
Above is the CVSS Sub-score Breakdown for CVE-2026-49457, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.
Below is the Impact Analysis for CVE-2026-49457, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.
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