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VulnerabilityPublished Updated

CVE-2026-33818: Go standard library encoding/asn1 · Uncontrolled Resource Consumption

Affects Go standard library encoding/asn1Source CVE Database V5

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Not known to be exploited · CVSS 7.5 High · fixed in 1.27.0-rc.3 : patch Go standard library encoding/asn1 soon.

Data as of 13 Nov 2026, 12:10 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
EPSS
0.5% chance of exploitation in 30 days – higher than 47% 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
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 13 Nov 2026.

What to do

Upgrade Go standard library 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

Upgrade to one of the fixed versions: 1.25.13, 1.26.6, or 1.27.0-rc.3. Applying these updates enforces a recursion limit in the Unmarshal function, preventing stack exhaustion. No other mitigation is indicated or required.

Description

CVE-2026-33818 is a high-severity vulnerability in the Go standard library's encoding/asn1 package. It involves uncontrolled resource consumption due to the lack of a recursion limit in the Unmarshal function, which can lead to stack exhaustion when parsing deeply nested or recursive ASN.1 structures. This flaw has been addressed in versions 1.25.13, 1.26.6, and 1.27.0-rc.3 of the Go standard library.

References

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