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CVE-2026-33818VulnerabilityPublished

Red Hat Security Advisory: gvisor-tap-vsock security update

Affects Red Hat gvisor-tap-vsockSource GCVE Database

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Mentioned vulnerabilities

Authoritative record:CVE-2026-33818· High 7.5

Not known to be exploited · CVSS 7.5 High · fixed in Red Hat package updates : patch Red Hat asn1 soon.

Data as of 11 Nov 2026, 13:27 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CISA-ADPCVSS 3.17.5
Patch
Available – fixed in 1.27.0-rc.3, 1.26.6, 1.25.13
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 13 Aug 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 11 Nov 2026.

What to do

Upgrade encoding/asn1 to 1.27.0-rc.3, 1.26.6 or 1.25.13.

Affected software

ProductAffectedFixed in
Go standard libraryencoding/asn1Affected
  • >=1.27.0-0 <1.27.0-rc.3
Fixed in
  • 1.27.0-rc.3
Go standard libraryencoding/asn1Affected
  • >=1.26.0-0 <1.26.6
Fixed in
  • 1.26.6
Go standard libraryencoding/asn1Affected
  • <1.25.13
Fixed in
  • 1.25.13
Goencoding/asn1pkg:golang/encoding/asn1Other threatsAffected
  • <1.25.13
  • >=1.26.0-0 <1.26.6
  • >=1.27.0-0 <1.27.0-rc.3
Fixed in
  • 1.25.13
  • 1.26.6
  • 1.27.0-rc.3

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 updated gvisor-tap-vsock packages for Red Hat Enterprise Linux 9 on multiple architectures that address these vulnerabilities. Users should apply the security update as detailed in the Red Hat advisory (RHSA-2026:98502) to remediate these issues. No additional mitigations are specified or required beyond applying the official patches.

Description

Red Hat has issued a security update for gvisor-tap-vsock, a Go-based replacement for libslirp and VPNKit. The update addresses multiple denial of service vulnerabilities and a man-in-the-middle vulnerability in various Go libraries used by gvisor-tap-vsock. These include excessive recursion in ASN.1 unmarshalling, unencrypted HTTP/2 connection issues, indefinite TLS KeyUpdate messages, crafted HTTP Range headers, multiple ECH outer extension references, memory limit bypass in multipart form parsing, and untrusted intermediate certificates allowing man-in-the-middle attacks. The update is rated as Important by Red Hat and affects Red Hat Enterprise Linux 9 on multiple architectures.

References

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