CVE-2026-42530
CRITICAL 9.2NGINX Open Source has a vulnerability in the ngx_http_v3_module module. When NGINX Open Source is configured to use the HTTP/3 QUIC module, a remote unauthenticated attacker along with conditions beyond their control can use a specially crafted HTTP/3 session to reopen a QPACK encoder stream. This may cause a Use-after-Free in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
Severe if exploited (CVSS 9.2), but no known exploitation and low modeled probability. Patch on a normal cadence.
Exploitation likelihood
3.3%chance of exploitation in 30 days · 87th percentile
Impact if exploited
9.2CVSS 4.0 · CRITICAL
- ConfidentialityHigh
- IntegrityHigh
- AvailabilityHigh
What an attacker needs
- ✓Access: Reachable over the network — no local access needed
- ✓Privileges: No account or privileges required
- ✓User interaction: No user interaction needed
- ⚠Complexity: Needs a race window or specific setup
- ✓Requirements: No special attack requirements
✓ lowers the bar for an attacker · ⚠ raises it
Affected
Products Nginx Open Source Red Hat Hardened Images Red Hat Enterprise Linux 10 Red Hat Enterprise Linux 8 Red Hat Enterprise Linux 9 Red Hat Lightspeed Proxy 1
Weakness (CWE)
- CWE-416: Use after free
CVSS vector
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N