Quick answers
- Is CVE-2026-63075 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-63075 being exploited in the wild.
- How severe is CVE-2026-63075?
- High severity, with a CVSS score of 7.5, published 25 August 2026.
- Which products and versions are affected?
- OpenSSL <UNKNOWN>.
- Is there a fix for CVE-2026-63075?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-63075 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-63075?
- Check whether you run OpenSSL 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
This is an algorithmic resource allocation vulnerability (CWE-770) in OpenSSL's QUIC stack. When the stack sends ACK-only packets, it retains the associated metadata in packet history structures regardless of whether the peer acknowledges them. An attacker can exploit this by completing a QUIC handshake, then sending repeated PING frames to force ACK-only responses from the target, while withholding acknowledgments of ack-eliciting packets. This causes unbounded memory growth on the connection. The vulnerability requires network-level access and successful QUIC handshake completion. The fix involves accounting for ACK-only transmissions in packet history watermarks without storing the packet metadata itself.
Affected products
- OpenSSL OpenSSL <UNKNOWN>
Timeline
- 2026-08-25: disclosed