2.2

CVE-2026-93601: rustls webpki Improper Certificate Validation

CVSS: 2.2v3.1LowAwaiting analysis
AliasesUBUNTU-CVE-2026-93601DEBIAN-CVE-2026-93601GHSA-xgp8-3hg3-c2mh
Published 18-09-2026Last modified 18-09-2026
Open JSON

Vulnerability summary

CVE-2026-93601 is a low (CVSS 2.2) Improper Certificate Validation vulnerability in rustls webpki. EPSS estimates a 0.18% chance of exploitation in the next 30 days, higher than 7.3% of scored vulnerabilities.

Overall risk
9/100
0100
Minimal · default modelHow is this calculated?
CVSS score
2.2/10
010
Low · v3.1 (CVE.org)
EPSS score
0.18%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 5 · Related 5
OPENSUSE-SU-2026:11936-1OPENSUSE-SU-2026:21982-1OPENSUSE-SU-2026:22016-1SUSE-SU-2026:23983-1SUSE-SU-2026:24014-1

Timeline

  1. 18-09-2026
    PublishedVulnerability first disclosed.
  2. 18-09-2026
    Last modifiedVulnerability information updated.

Description

rustls-webpki (the Rust webpki fork used by rustls) versions >= 0.101.0 and prior to 0.103.12 and 0.104.0-alpha.6 incorrectly accepted permitted-subtree DNS name constraints for certificates asserting a wildcard name. For example, a name constraint of accept.example.com was treated as satisfied by a certificate for *.example.com, which could feasibly assert reject.example.com — a name outside the permitted subtree. Because name constraints are restrictions applied to otherwise properly issued certificates, the issue is only reachable after signature verification succeeds and requires a misissued wildcard certificate to exploit.

CVSS metrics

8 scores · 5 sources · 2 versions

EPSS trend

Probability

0.18%

Chance of exploitation in the next 30 days

Percentile

7%

Versus all other CVEs

30-day change

0.00 pp

From 0.18% on 20-09-2026

20-09-202620-10-2026
EPSS score
0.18%

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

Crates.Io1 product
  • rustls-webpki≥ 0.101.0, < 0.103.12 | ≥ 0.104.0-alpha.1, < 0.104.0-alpha.6
Debian1 product
  • rust-rustls-webpkiAll versions (No fix recorded) | < 0.103.13+ds-1
Rustls1 product
  • webpki≥ 0.101.0, < 0.103.12 | ≥ 0.104.0-alpha.1, < 0.104.0-alpha.6
Ubuntu1 product
  • rust-rustls-webpkiAll versions (No fix recorded)

4 vendors · 4 products

References

8 links