3.7

CVE-2026-35191: openssl Expected Behavior Violation

CVSS: 3.7v3.1LowAnalyzed
AliasesUBUNTU-CVE-2026-35191DEBIAN-CVE-2026-35191CGA-7x9f-q5p7-5c8m
Published 29-09-2026Last modified 30-09-2026
Open JSON

Vulnerability summary

CVE-2026-35191 is a low (CVSS 3.7) Expected Behavior Violation vulnerability in openssl. EPSS estimates a 0.36% chance of exploitation in the next 30 days, higher than 27.9% of scored vulnerabilities.

Overall risk
15/100
0100
Low · default modelHow is this calculated?
CVSS score
3.7/10
010
Low · v3.1 (CVE.org)
EPSS score
0.36%
0%100%
Low · Change unavailable
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 5 · Related 2
MGASA-2026-0481RHSA-2026:74162RHSA-2026:74166SUSE-SU-2026:4414-1USN-8847-1

Timeline

  1. 29-09-2026
    PublishedVulnerability first disclosed.
  2. 30-09-2026
    Last modifiedVulnerability information updated.

Description

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.

CVSS metrics

5 scores · 5 sources · 1 version

EPSS trend

Probability

0.36%

Chance of exploitation in the next 30 days

Percentile

28%

Versus all other CVEs

30-day change

Change unavailable

Change unavailable

30-09-202619-10-2026
EPSS score
0.36%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Ubuntu4 products
  • edk2All versions (No fix recorded)
  • edk2-hweAll versions (No fix recorded)
  • nodejsAll versions (No fix recorded)
  • openssl< 3.5.5-1ubuntu3.6
Chainguard2 products
  • openssl-provider-fips-3.6.0All versions (No fix recorded)
  • openssl-provider-fips-3.6.0-dbgAll versions (No fix recorded)
Debian1 product
  • openssl< 3.5.7-1~deb13u3 | < 3.6.5-1
Openssl1 product
  • openssl≥ 3.5.0, < 3.5.9 | ≥ 3.6.0, < 3.6.5 | ≥ 4.0.0, < 4.0.3

4 vendors · 8 products

References

10 links