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CVE-2026-93601VulnerabilityPublished Updated

Microsoft · rustls webpki 0.101.0 before 0.103.12 Name Constraint Bypass

Affects MicrosoftSource GCVE Database

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Authoritative record:CVE-2026-93601· Low 2.1

Not known to be exploited · CVSS 2.1 Low : upgrade to 0.104.0-alpha.6 or 0.103.12 when convenient.

Data as of 2 Nov 2026, 10:58 UTC

CVSS 4.0 base score
2.1Low
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 10% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 0.104.0-alpha.6, 0.103.12
CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 18 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2 Nov 2026.

What to do

Upgrade webpki and rustls/webpki to 0.104.0-alpha.6 or 0.103.12.

Affected software

ProductAffectedFixed in
rustlswebpkiAffected
  • >=0.104.0-alpha.1 <0.104.0-alpha.6
Fixed in
  • 0.104.0-alpha.6
rustlswebpkiAffected
  • >=0.101.0 <0.103.12
Fixed in
  • 0.103.12
crates.iorustls/webpkipkg:cargo/rustls/webpkiOther threatsAffected
  • >=0.101.0 <0.103.12
  • >=0.104.0-alpha.1 <0.104.0-alpha.6
Fixed in
  • 0.103.12
  • 0.104.0-alpha.6

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

A vulnerability identified as CVE-2026-93601 affects rustls webpki versions before 0.103.12, specifically version 3.0 of the Microsoft product. The issue involves a Name Constraint Bypass, which relates to certificate validation weaknesses. No CVSS score or detailed impact information is provided.

References

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