# CVE-2026-78661: Avoid quadratic complexity when coalescing text nodes in html in golang.org/x/net CVE-2026-78661 is fixed in golang-golang-x-net on 1 platform by DEBIAN-CVE-2026-78661 (version 1:0.62.0-1), released November 3, 2026. It is not reported as exploited. Patch Radar priority: High. - Web page: https://patchblox.com/security/cve/CVE-2026-78661 - Priority: High - CVSS: 7.5 (Moderate) - EPSS: 0.0041 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Oct 27, 2026 - Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-78661 ## 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") 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. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | golang-golang-x-net Debian 14 | 1:0.62.0-1 | [DEBIAN-CVE-2026-78661](https://patchblox.com/security/data/fix/linux/debian-cve-2026-78661.md) | Nov 3, 2026 | --- Data as of 2026-11-09T07:25:28Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.