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No exploitation reportedFix available

CVE-2026-78661

Avoid quadratic complexity when coalescing text nodes in html in golang.org/x/net

No exploitation reported by the sources we read.

  • Published2026-10-27
  • Fixed in0.62.0
  • WeaknessCWE-407

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

When coalescing adjacent text nodes in addText and fosterParent, appending to an existing TextNode's Data via string concatenation (n.Data += text) reallocated and copied the accumulated string on every token. Inputs containing many short text runs separated by ignored end tags (such as "a</x>") caused O(n^2) allocations and byte copies. Accumulate coalesced text in per-node byte slices during parsing and materialize Data strings once at the end of parse.

Timeline

dates in UTC
  1. 2026-10-2721:38CVE publishedCNA

Versions per branch

OSV
golang.org/x/net
BranchAffectedFixed in
0.62< 0.62.00.62.0

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA1 product

As Go, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • golang.org/x/net/htmlother versions: not affected

    https://pkg.go.dev

    Affected
    • < 0.62.0fixed in 0.62.0semver

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2026-10-27

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • aws-efs-csi-driverMinimOSall versions · fixed in 3.5.4-r0and 1 other package
  • aws-otel-collectorMinimOSall versions · fixed in 0.51.0-r0and 1 other package
  • cert-manager-1.20Wolfiall versions · fixed in 1.20.5-r0and 4 other packages
  • cert-manager-1.20Chainguardall versions · fixed in 1.20.5-r0and 4 other packages
  • cert-manager-fips-1.20MinimOSall versions · fixed in 1.20.5-r0and 5 other packages
  • cilium-1.19Wolfiall versions · fixed in 1.19.10-r1
  • cilium-1.19Chainguardall versions · fixed in 1.19.10-r1
  • cloudnative-pgMinimOSall versions · no fixed version listedand 208 other packages

98 more package ranges on OSV.dev

Full record on NVD

Fix

  1. Update golang.org/x/net to 0.62.0

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Metasploit modules
none listed
Metasploit Framework

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Published
2026-10-27
Last Modified
2026-11-04
NVD status
Deferred
GitHub Advisory
GHSA-75pg-wvh3-34jr

Frequently asked questions

What is CVE-2026-78661?

When coalescing adjacent text nodes in addText and fosterParent, appending to an existing TextNode's Data via string concatenation (n.Data += text) reallocated and copied the accumulated string on every token. Inputs containing many short text runs separated by ignored end tags (such as "a</x>") caused O(n^2) allocations and byte copies. Accumulate coalesced text in per-node byte slices during parsing and materialize Data strings once at the end of parse.

Is CVE-2026-78661 actively exploited?

Active exploitation of CVE-2026-78661 has not been confirmed. Its EPSS score was 0.2% on 2026-11-04, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-78661?

CVE-2026-78661 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.

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