CVE-2026-33811

When using LookupCNAME with the cgo DNS resolver, a very long CNAME response can trigger a double-free of C memory and a crash.

CVSS v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://go.dev/cl/767860	Patch
https://go.dev/issue/78803	Issue Tracking
https://groups.google.com/g/golang-announce/c/qcCIEXso47M	Mailing List Third Party Advisory
https://pkg.go.dev/vuln/GO-2026-4981	Vendor Advisory

Configurations

Configuration 1 (hide)

OR	cpe:2.3:a:golang:go::::::::
	cpe:2.3:a:golang:go::::::::

History

12 May 2026, 20:23

Type	Values Removed	Values Added
CPE		cpe:2.3:a:golang:go::::::::
References	~~() https://go.dev/cl/767860 -~~	() https://go.dev/cl/767860 - Patch
References	~~() https://go.dev/issue/78803 -~~	() https://go.dev/issue/78803 - Issue Tracking
References	~~() https://groups.google.com/g/golang-announce/c/qcCIEXso47M -~~	() https://groups.google.com/g/golang-announce/c/qcCIEXso47M - Mailing List, Third Party Advisory
References	~~() https://pkg.go.dev/vuln/GO-2026-4981 -~~	() https://pkg.go.dev/vuln/GO-2026-4981 - Vendor Advisory
First Time		Golang Golang go
CWE		CWE-415

08 May 2026, 15:16

Type	Values Removed	Values Added
CVSS	v2 : ~~unknown~~ v3 : ~~unknown~~	v2 : unknown v3 : 7.5

07 May 2026, 20:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-05-07 20:16

Updated : 2026-05-12 20:23

NVD link : CVE-2026-33811

Mitre link : CVE-2026-33811

CVE.ORG link : CVE-2026-33811

JSON object : View

Products Affected

golang

go

CWE

CWE-415

Double Free

{"id": "CVE-2026-33811", "cveTags": [], "metrics": {"cvssMetricV31": [{"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.5, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}, "impactScore": 3.6, "exploitabilityScore": 3.9}, {"type": "Secondary", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.5, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}, "impactScore": 3.6, "exploitabilityScore": 3.9}]}, "published": "2026-05-07T20:16:42.770", "references": [{"url": "https://go.dev/cl/767860", "tags": ["Patch"], "source": "security@golang.org"}, {"url": "https://go.dev/issue/78803", "tags": ["Issue Tracking"], "source": "security@golang.org"}, {"url": "https://groups.google.com/g/golang-announce/c/qcCIEXso47M", "tags": ["Mailing List", "Third Party Advisory"], "source": "security@golang.org"}, {"url": "https://pkg.go.dev/vuln/GO-2026-4981", "tags": ["Vendor Advisory"], "source": "security@golang.org"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Primary", "source": "nvd@nist.gov", "description": [{"lang": "en", "value": "CWE-415"}]}], "descriptions": [{"lang": "en", "value": "When using LookupCNAME with the cgo DNS resolver, a very long CNAME response can trigger a double-free of C memory and a crash."}], "lastModified": "2026-05-12T20:23:02.333", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:golang:go:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "1C966EF3-C51C-4239-B5FC-C44A5202FEC8", "versionEndExcluding": "1.25.10"}, {"criteria": "cpe:2.3:a:golang:go:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "522E4CD0-2B99-4363-9C78-0BAFD988A2D6", "versionEndExcluding": "1.26.3", "versionStartIncluding": "1.26.0"}], "operator": "OR"}]}], "sourceIdentifier": "security@golang.org"}