CVE-2026-33818Network attack vector

Application crash via unbounded ASN.1 recursion

Published Aug 13, 2026 · Updated Aug 25, 2026

Denial of service in Go standard library encoding/asn1 allows remote attackers to crash applications via deeply nested DER input. Unmarshal and UnmarshalWithParams recursively descend through parseField and parseSequenceOf without limiting nesting depth, exhausting the goroutine stack. An application must pass attacker-controlled DER into these functions; exploitation terminates the hosting process rather than altering or disclosing data.

CVSS severity7.5
High
EPSS probability0.57%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Go standard library encoding/asn1 allows remote attackers to crash applications via deeply nested DER input. Unmarshal and UnmarshalWithParams recursively descend through parseField and parseSequenceOf without limiting nesting depth, exhausting the goroutine stack. An application must pass attacker-controlled DER into these functions; exploitation terminates the hosting process rather than altering or disclosing data.

The record

CVE
CVE-2026-33818
Published
Aug 13, 2026
Updated
Aug 25, 2026
Vendor
Go standard library
Product
encoding/asn1
Classifications
CWE-400, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 13, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <1.25.13
  2. Affected versionversion=1.26.0-0 <1.26.6
  3. Affected versionversion=1.27.0-0 <1.27.0-rc.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Go standard library · encoding/asn1version=0 <1.25.13; version=1.26.0-0 <1.26.6; version=1.27.0-0 <1.27.0-rc.3

Published CVSS scores

7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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