CVE-2026-26278
Description
fast-xml-parser allows users to validate XML, parse XML to JS object, or build XML from JS object without C/C++ based libraries and no callback. In versions 4.1.3 through 5.3.5, the XML parser can be forced to do an unlimited amount of entity expansion. With a very small XML input, it’s possible to make the parser spend seconds or even minutes processing a single request, effectively freezing the application. Version 5.3.6 fixes the issue. As a workaround, avoid using DOCTYPE parsing by `processEntities: false` option.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
| OS | Version | Status | Fixed in |
|---|---|---|---|
| sles | affected | | |
| debian | bookworm | undetermined | |
| debian | forky | undetermined | |
| debian | sid | undetermined | |
| debian | trixie | undetermined | |
Package impact
| Ecosystem | Package | Vulnerable | Fixed |
|---|---|---|---|
| npm | fast-xml-parser | >=4.1.3,<4.5.4 | 4.5.4 |
| npm | fast-xml-parser | >=5.0.0,<5.3.6 | 5.3.6 |
References
- https://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-jmr7-xgp7-cmfj
- https://nvd.nist.gov/vuln/detail/CVE-2026-26278
- https://github.com/NaturalIntelligence/fast-xml-parser/commit/910dae5be2de2955e968558fadf6e8f74f117a77
- https://github.com/NaturalIntelligence/fast-xml-parser
- https://github.com/NaturalIntelligence/fast-xml-parser/releases/tag/v5.3.6
- https://www.suse.com/security/cve/CVE-2026-26278.html
- https://security-tracker.debian.org/tracker/CVE-2026-26278
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.