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TI-2026-27344 Aliases CVE-2026-35191GHSA-5p85-47cf-3663

QUIC Unvalidated Amplification Credit may be Over Accounted

Priority LOW 19CWE-440Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
High
Impact type
—
Confidentiality · integrity · availability
None · None · Low
Fix status
Partial Red Hat: 1 fixed, 7 without a fix

Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA and Red Hat.

Summary

Issue summary: The OpenSSL QUIC server, when configured to not preform address validation, can be forced to count incoming packets multiple times in its unvalidated credit computation, leading to a violation of the RFC 9000 unvalidated connection amplification limit of 3 times the amount of data received. Impact summary: A remote attacker able to spoof packets to a server using the OpenSSL QUIC implementation might use the server for an amplification of a DDoS attack. CWE: CWE-440: Expected Behavior Violation Description: OpenSSL's QUIC stack, when operating as a server, enforces client address validation (RFC 9000, Section 8), to confirm the peer address is not used for a traffic amplification attack. If this feature is disabled on the server, the QUIC stack limits the amount of server data that can be sent to 3 times the amount of data received from the peer address, until such time as the TLS handshake is completed. The OpenSSL QUIC server, when operating in non-validation mode, adds the length of the whole datagram received to the unvalidated credit limit when processing each QUIC packet in the datagram. A remote peer may, after establishing a connection with an initial client hello frame, send a subsequent datagram containing multiple QUIC packets, leading the server to account the entire datagram length for each packet in the datagram, resulting in the server believing that the peer has sent more data than it actually has, thereby violating the 3x amplification limit mandated by the RFC. FIPS impact: no As the QUIC stack lives outside the FIPS module boundary, no FIPS modules are affected by this CVE.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00723 54th percentileScored 2026-11-07
Fix Partial OpenSSL (OpenSSL): 4.0.3, 3.6.5, 3.5.9Red Hat: 2 advisoriesRed Hat: 1 fixed, 7 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
OpenSSLOpenSSL4.0.0 to before 4.0.3; 3.6.0 to before 3.6.5; 3.5.0 to before 3.5.94.0.3, 3.6.5, 3.5.9Patch availableCNA
  • OpenSSL VendorOpenSSL Affected 4.0.0 to before 4.0.3; 3.6.0 to before 3.6.5; 3.5.0 to before 3.5.9 Fixed in 4.0.3, 3.6.5, 3.5.9 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*3.5.0 to before 3.5.9; 3.6.0 to before 3.6.5; 4.0.0 to before 4.0.3VulnerableOpenSSL
  • cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:* Versions 3.5.0 to before 3.5.9; 3.6.0 to before 3.6.5; 4.0.0 to before 4.0.3 Vulnerable ·OpenSSL

Remediation

  • Fix · CNA OpenSSL (OpenSSL) Fixed in 4.0.3, 3.6.5, 3.5.9

Red Hat 2 advisories

  • RHSA-2026:74166 Released 2026-09-30 · Red Hat rating Important
    Red Hat Hardened Images RPMs bug fix and enhancement update
    • Red Hat Hardened Images openssl3-1:3.5.9-0.1.hum1@src, openssl3-devel-1:3.5.9-0.1.hum1@aarch64, openssl3-devel-1:3.5.9-0.1.hum1@x86_64 +4
  • RHSA-2026:74162 Released 2026-09-30 · Red Hat rating Important
    Red Hat Hardened Images RPMs bug fix and enhancement update
    • Red Hat Hardened Images openssl-1:3.5.9-0.1.hum1@aarch64, openssl-1:3.5.9-0.1.hum1@src, openssl-1:3.5.9-0.1.hum1@x86_64 +12

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Advisory ·

    OpenSSL — openssl-library.org/news/secadv/20260929.txt

    14 records Highest priority Priority MEDIUM 3 MEDIUM, 11 LOW

    Other records, highest priority first

    • TI-2026-58283 DTLS Retransmits Handshake Messages From a Stale Buffer OffsetPriority MEDIUM 43
    • TI-2026-58285 QUIC: Unbounded RETIRE_CONNECTION_ID BacklogPriority MEDIUM 40
    • TI-2026-39654 QUIC STREAM Fragment Metadata DoSPriority MEDIUM 40
    Show all 14 records → Advisory →

Vendor assessments

Red Hat

Red Hat rating: Low. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Developer Hub 1AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux 10AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux 9AffectedNo fix yet
Red Hat OpenShift AI (RHOAI)Affected—
Red Hat OpenShift Container Platform 4AffectedNo fix yet: Fix deferred
Red Hat OpenShift Container Platform 5AffectedNo fix yet: Fix deferred
Red Hat Satellite 6AffectedNo fix yet: Fix deferred
Red Hat Hardened ImagesFixed RHSA-2026:74162, RHSA-2026:74166
Not affected: 6 products
  • Red Hat Enterprise Linux 6
  • Red Hat Enterprise Linux 7
  • Red Hat Enterprise Linux 8
  • Red Hat Hardened Images
  • Red Hat JBoss Core Services
  • Red Hat OpenShift AI (RHOAI)

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-35191
  2. 2026-10-03 Alias added: GHSA-5p85-47cf-3663
  3. 2026-10-11 Affected versions changed · Red Hat
  4. 2026-10-16 Affected versions changed · Red Hat
  5. 2026-10-25 EPSS moved to the 50th–90th percentile
  6. 2026-10-27 Affected versions changed · Red Hat
  7. 2026-10-30 Affected versions changed · Red Hat
  8. 2026-11-06 Affected versions changed · Red Hat

References

Patch 3

Advisory 1

  • TI-2022-01915 The c_rehash script allows command injection CVSS 3.1CRITICAL 9.8
  • TI-2021-02645 SM2 Decryption Buffer Overflow CVSS 3.1CRITICAL 9.8
  • TI-2009-03392 The TLS protocol, and the SSL protocol 3.0 and possibly earlier, as used in Microsoft… CVSS 3.1CRITICAL 9.8
  • TI-2022-01176 The c_rehash script allows command injection CVSS 3.1CRITICAL 9.8
  • TI-2014-00154 The (1) TLS and (2) DTLS implementations in OpenSSL 1.0.1 before 1.0.1g do not properly… KEVCVSS 3.1HIGH 7.5
  • TI-2025-14107 Stack buffer overflow in CMS (Auth)EnvelopedData parsing CVSS 3.1HIGH 8.8
See all 312 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences