Vulnerability in katex (CVE-2026-103923)
Summary
Vulnerability in katex (CVE-2026-103923). Risk of unauthorized operations or information disclosure. Exploitable via Object.prototype. Mitigation: upgrade to 0.18.2 or later.
Original description
The description as published by the source.
Impact
KaTeX can act as a read-side prototype pollution gadget in applications where Object.prototype has already been polluted, or where an attacker can influence the prototype of the renderer options object. (KaTeX does not enable said prototype pollution. This advisory applies when combining KaTeX with other vulnerable software that allows for prototype pollution.)
Affected versions may treat inherited properties from Object.prototype as renderer options, internal setting metadata, or namespace entries. In particular, an inherited trust value will be treated as though the application explicitly enabled trusted rendering, rather than using the documented default of false.
With attacker-controlled mathematical expressions, this can produce links capable of user-interaction cross-site scripting or load attacker-selected external resources. Exploitation requires the consuming application to insert KaTeX output into a web page without a separate sanitizer. (KaTeX does not execute scripts merely by rendering an expression.)
Other inherited settings can alter rendering behavior or resource limits. Inherited setting metadata can affect how defaults and supplied options are processed, while inherited namespace properties can be mistaken for defined macros or other internal values.
Patches
Upgrade to KaTeX v0.18.2 to remove this vulnerability.
Workarounds
- Address any prototype-pollution vulnerability in the application or its dependencies.
- `delete Obj…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-103923 has been found in katex.
Attackers can target a specific entry point like Object.prototype over the network to misuse the product.
Risk of unauthorized operations or information disclosure.
What to do: upgrade katex to 0.18.2 or later.
If unsure, ask your IT team or search "katex CVE-2026-103923" on the vendor's site.
CVE-2026-103923 (katex) — CWE-807
Attack surface: Object.prototype / trust / false / default
Patched: 0.18.2 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-807) exists in katex. Attackers reach the vulnerable code path via Object.prototype.
Check the vendor advisory for the affected versions of katex. Attack surface: Object.prototype / trust / false / default.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to 0.18.2.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'katex' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'katex' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
katexを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade katex to 0.18.2ステージング環境で 0.18.2 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
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3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。