7.5

CVE-2026-5680: undertow

CVSS: 7.5v3.1HighAwaiting analysis
AliasesUBUNTU-CVE-2026-5680DEBIAN-CVE-2026-5680
Published 27-08-2026Last modified 14-10-2026
Open JSON

Vulnerability summary

CVE-2026-5680 is a high (CVSS 7.5) vulnerability in undertow. EPSS estimates a 1.10% chance of exploitation in the next 30 days, higher than 65% of scored vulnerabilities.

Overall risk
30/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.5/10
010
High · v3.1 (CVE.org)
EPSS score
1.10%
0%100%
Low · +0.69 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 3
RHSA-2026:70228RHSA-2026:70229RHSA-2026:70230

Timeline

  1. 27-08-2026
    PublishedVulnerability first disclosed.
  2. 14-10-2026
    Last modifiedVulnerability information updated.

Description

A flaw was found in Undertow. A remote attacker could exploit this vulnerability by sending specially crafted WebSocket messages with permessage-deflate negotiated. This could lead to excessive memory consumption due to the PerMessageDeflateFunction.largerBuffer() method using exponential doubling, resulting in a Denial of Service (DoS) for the affected application.

CVSS metrics

4 scores · 4 sources · 1 version

EPSS trend

Probability

1.10%

Chance of exploitation in the next 30 days

Percentile

65%

Versus all other CVEs

30-day change

+0.69 pp

From 0.40% on 19-09-2026

19-09-202619-10-2026
EPSS score
1.10%

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

Debian1 product
  • undertowAll versions (No fix recorded)
Ubuntu1 product
  • undertowAll versions (No fix recorded)

2 vendors · 2 products

References

9 links