CVE-2026-33810: Go standard library crypto/x509 · Improper Certificate Validation
Affects Go standard library crypto/x509Source CVE Database V5
Not known to be exploited · CVSS 7.5 High : upgrade to 1.26.2 soon.
Data as of 29 Oct 2026, 19:04 UTC
- 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:NExploitation evidence
Disclosed: evidence found.
CVE published 8 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
| Go standard librarycrypto/x509 | Affected
| Fixed in
|
Gocrypto/x509pkg:golang/crypto/x509Other threats | Affected
| Fixed in
|
Gogithub.com/golang/go/src/crypto/x509pkg:golang/github.com/golang/go/src/crypto/x509Other threats | Affected
| 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
- go.dev/cl/763763 (opens in a new tab)
- go.dev/issue/78332 (opens in a new tab)
- groups.google.com/g/golang-announce/c/0uYbvbPZRWU (opens in a new tab)
- pkg.go.dev/vuln/GO-2026-4866 (opens in a new tab)
- openwall.com/lists/oss-security/2026/04/19/4 (opens in a new tab)
- openwall.com/lists/oss-security/2026/04/20/1 (opens in a new tab)
- access.redhat.com/security/cve/CVE-2026-33810 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2456335 (opens in a new tab)
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33810.json (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:14391 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:36796 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:28047 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:39810 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:34365 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:19719 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:19144 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:19135 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:19721 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:19720 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:19353 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:10155 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:26571 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:25089 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:47952 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:26585 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:22862 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:22347 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:23345 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:29854 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:26568 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:13545 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:36651 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:40945 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:40118 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:7291 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:22485 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:41928 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:10158 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:21772 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:9385 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:24478 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:42043 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:22960 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:42047 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:22958 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:22962 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:42050 (opens in a new tab)
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- access.redhat.com/errata/RHSA-2026:42051 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:22961 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:42049 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:21769 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:51033 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:54757 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:51288 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:34192 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:34196 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:34197 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:57126 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:19714 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:59546 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:49703 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:49702 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:56143 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:57649 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:49712 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:56223 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:61313 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:61253 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:61907 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:62577 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:62578 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:63332 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:65534 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:65359 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:65880 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:65126 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:66327 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:65895 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:67149 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:67134 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:67160 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:67159 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:67517 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:67518 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:68334 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:68504 (opens in a new tab)