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VulnerabilityPublished Updated

CVE-2026-33810: Go standard library crypto/x509 · Improper Certificate Validation

Affects Go standard library crypto/x509Source CVE Database V5

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Not known to be exploited · CVSS 7.5 High : upgrade to 1.26.2 soon.

Data as of 29 Oct 2026, 19:04 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 27% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 1.26.2
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 8 Apr 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 29 Oct 2026.

What to do

Upgrade Go standard library crypto/x509 to 1.26.2.

Affected software

ProductAffectedFixed in
Go standard librarycrypto/x509Affected
  • >=1.26.0-0 <1.26.2
Fixed in
  • 1.26.2
Gocrypto/x509pkg:golang/crypto/x509Other threatsAffected
  • >=1.26.0-0 <1.26.2
Fixed in
  • 1.26.2
Gogithub.com/golang/go/src/crypto/x509pkg:golang/github.com/golang/go/src/crypto/x509Other threatsAffected
  • =1.26.0-0
Fixed in–

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

AI-suggested

Red Hat has released security updates that fix this vulnerability in their build of Cryostat 4 on RHEL 9. Users should apply the relevant security updates as provided by Red Hat to remediate this issue. Before applying the update, ensure all previously released errata relevant to your system have been applied. For details on applying updates, refer to Red Hat's official guidance. No other mitigations are specifically noted by the vendor advisory. Patch status is confirmed as fixed in the updated Red Hat packages.

Description

When verifying a certificate chain containing excluded DNS constraints, these constraints are not correctly applied to wildcard DNS SANs which use a different case than the constraint. This only affects validation of otherwise trusted certificate chains, issued by a root CA in the VerifyOptions.Roots CertPool, or in the system certificate pool.

References

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