Vulnerability in microdot (CVE-2026-42874)
Summary
Vulnerability in microdot (CVE-2026-42874). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 2.6.1 or later.
Original description
The description as published by the source.
Impact
The Response.set_cookie() method does not sanitize its string arguments, and in particular will not detect the presence of the \r\n sequence in them. This can be a potential source of header injection attacks.
For a header injection attack through this issue to be possible, an attacker must first infiltrate the client (for example through an independent XSS attack), so that it can send malicious information that is destined to be stored in a cookie by the server on behalf of the victim. An attacker that infiltrates one client can only orchestrate a header injection attack for that client, all other clients that were not infiltrated are safe.
Patches
Upgrade to version 2.6.1.
Workarounds
Do not pass untrusted data to the Response.set_cookie() method.
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-2026-42874 has been found in microdot.
Risk of unauthorized operations or information disclosure. CVSS score: 3.7/10.
What to do: upgrade microdot to 2.6.1 or later.
If unsure, ask your IT team or search "microdot CVE-2026-42874" on the vendor's site.
CVE-2026-42874 (microdot) — CWE-113 / CVSS v3 3.7
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 2.6.1 — apply immediately
Workaround: Do not pass untrusted data to the Response.set_cookie() method.
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-113) exists in microdot.
Check the vendor advisory for the affected versions of microdot.
Severity: Low (CVSS 3.7/10). Risk of unauthorized operations or information disclosure.
Update to 2.6.1.
Workaround: Do not pass untrusted data to the Response.set_cookie() method.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'microdot' . 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
-
1Identify exposure identify
grep -r 'microdot' . | 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
microdotを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply temporary workaround mitigate
Do not pass untrusted data to the `Response.set_cookie()` method.パッチが適用されるまでの応急処置として、Do not pass untrusted data to the
Response.set_cookie()method. を実施。回避策の副作用 (機能低下) を確認した上で。 -
3Apply patch patch
Upgrade microdot to 2.6.1ステージング環境で 2.6.1 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。
-
4Post-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。
Affected packages
References
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com
- web github.com
- web github.com