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CVE-2026-39821VulnerabilityPublished Updated

Red Hat Security Advisory: golang security, bug fix, and enhancement update

Affects Red Hat golang security,Source GCVE Database

0

Mentioned vulnerabilities

Authoritative record:CVE-2026-39821· Critical 9.6

Not known to be exploited · CVSS 9.6 Critical · fixed in Red Hat package updates : patch Red Hat http as a priority.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score
9.6Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
1.8% chance of exploitation in 30 days – higher than 78% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 1.27.0-rc.3, 1.26.6, 1.25.13 +1
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 22 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: 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 26 Oct 2026.

What to do

Upgrade net/http and net/http/internal/http2 to 1.27.0-rc.3, 1.26.6 or 1.25.13; golang.org/x/net/idna to 0.55.0.

Affected software

ProductAffectedFixed in
Go standard librarynet/httpAffected
  • >=1.27.0-0 <1.27.0-rc.3
Fixed in
  • 1.27.0-rc.3
Go standard librarynet/httpAffected
  • >=1.26.0-0 <1.26.6
Fixed in
  • 1.26.6
Go standard librarynet/httpAffected
  • <1.25.13
Fixed in
  • 1.25.13
Go standard librarynet/http/internal/http2Affected
  • >=1.27.0-0 <1.27.0-rc.3
Fixed in
  • 1.27.0-rc.3
Go standard librarynet/http/internal/http2Affected
  • >=1.26.0-0 <1.26.6
Fixed in
  • 1.26.6
Go standard librarynet/http/internal/http2Affected
  • <1.25.13
Fixed in
  • 1.25.13

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

Description

The golang packages provide the Go programming language compiler. Security Fix(es): * golang.org/x/net/idna: golang: golang.org/x/net/idna: Privilege escalation via incorrect Punycode label processing (CVE-2026-39821) * os: golang: Go os.Root: Symlink following vulnerability allows directory traversal (CVE-2026-39822) Bug Fix(es) and Enhancement(s): * Update Go to version 1.26.5+1 [rhel-9.8.z] (JIRA:RHEL-193476) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

References

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