CVE-2026-78661: golang.org/x/net/html · Inefficient Algorithmic Complexity
Affects golang.org/x/net/htmlSource CVE Database V5
Not known to be exploited : upgrade to 0.62.0 when convenient.
Data as of 27 Oct 2026, 22:01 UTC
Rated Medium by Threat Radar's AI analysis · CVSS not yet scored by NVD
- Patch
- Available – fixed in 0.62.0
Exploitation evidence
Disclosed: evidence found.
CVE published 27 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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 26 Oct 2026.
What to do
Upgrade golang.org/x/net/html to 0.62.0.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| golang.org/x/netgolang.org/x/net/html | Affected
| Fixed in
|
Gogolang.org/x/net/htmlpkg:golang/golang.org/x/net/htmlOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A fix is available in golang.org/x/net/html version 0.62.0. Users should upgrade to version 0.62.0 or later to remediate this inefficiency. No additional mitigation steps are required beyond applying the official fix.
Description
CVE-2026-78661 is an inefficient algorithmic complexity vulnerability in the golang.org/x/net/html package. The issue occurs when coalescing adjacent text nodes by repeatedly concatenating strings, causing O(n^2) allocations and byte copies for inputs with many short text runs separated by ignored end tags. This inefficiency was fixed in version 0.62.0 by accumulating text in byte slices and converting to strings only once after parsing.