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CVE-2026-4271 Redhat CVE debrief

CVE-2026-4271 was published on 2026-03-17 and later modified on 2026-05-11. According to the official CVE and NVD records, the issue is a use-after-free in libsoup's HTTP/2 server implementation. A remote attacker can send specially crafted HTTP/2 requests that cause authentication failures, leading the application to access freed memory and potentially crash. The documented impact is denial of service, with NVD assigning CVSS 3.1 5.3 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L).

Vendor
Redhat
Product
CVE-2026-4271
CVSS
MEDIUM 5.3
CISA KEV
Not listed in stored evidence
Original CVE published
2026-03-17
Original CVE updated
2026-05-11
Advisory published
2026-03-17
Advisory updated
2026-05-11

Who should care

Administrators and developers running applications that use libsoup, especially exposed HTTP/2 services and Red Hat environments referenced in the NVD CPEs and vendor advisories.

Technical summary

The vulnerability is classified as CWE-416 (Use After Free). NVD and Red Hat reference a flaw in libsoup's HTTP/2 server handling where authentication-failure paths can leave freed memory reachable, allowing a remote, unauthenticated attacker to trigger instability or crashes. The source corpus ties the issue to libsoup and lists affected Red Hat Enterprise Linux CPEs alongside the library CPE.

Defensive priority

Medium. Raise priority for internet-facing or high-availability services that rely on libsoup HTTP/2, because the issue is remotely triggerable and can cause service disruption.

Recommended defensive actions

  • Review Red Hat's CVE and errata pages for the applicable package or platform guidance.
  • Inventory systems and applications that link against libsoup, especially HTTP/2-enabled services.
  • Apply vendor updates or mitigation guidance as soon as they are available for your environment.
  • Monitor affected services for unexpected crashes or repeated authentication-related failures.
  • If you maintain a product using libsoup, validate whether your release includes the vendor's fix before redeploying.

Evidence notes

All statements are grounded in the supplied official records: the CVE description, NVD metadata, and Red Hat-linked references. The NVD record provides the CVSS vector, CWE-416 mapping, and affected CPEs. The Red Hat references include the security advisory, bug tracker entry, and GNOME libsoup issue reference. No fixed version numbers were present in the supplied corpus, so remediation guidance is limited to vendor-directed updates.

Official resources

Publicly disclosed through the official CVE record and NVD on 2026-03-17, with the NVD record updated on 2026-05-11. The supplied corpus also includes Red Hat advisory and issue-tracking references.