Vulnerability in symfony/mailomat-mailer (CVE-2026-48747)
Summary
Vulnerability in symfony/mailomat-mailer (CVE-2026-48747). Risk of unauthorized operations or information disclosure. Exploitable via md4. Mitigation: upgrade to 8.0.13 or later.
Original description
The description as published by the source.
Symfony is a PHP framework for web and console applications and a set of reusable PHP components. Prior to 7.4.13 and 8.0.13, MailomatRequestParser::validateSignature() parsed X-MOM-Webhook-Signature as algo=signature and passed the request-selected algorithm to hash_hmac(), allowing a signature algorithm downgrade instead of enforcing Mailomat's documented SHA-256 webhook signature. This issue is fixed in versions 7.4.13 and 8.0.13.
Source: GitHub Security Advisories (Global) 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-2026-48747 has been found in symfony/mailomat-mailer.
Attackers can target a specific entry point like md4 over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.3/10.
What to do: upgrade symfony/mailomat-mailer to 8.0.13 or later.
If unsure, ask your IT team or search "symfony/mailomat-mailer CVE-2026-48747" on the vendor's site.
CVE-2026-48747 (symfony/mailomat-mailer) — CWE-347 / CVSS v3 5.3
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: md4 / md5 / ripemd128
Patched: 8.0.13 — 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-347) exists in symfony/mailomat-mailer. Attackers reach the vulnerable code path via md4 without authentication.
Check the vendor advisory for the affected versions of symfony/mailomat-mailer. Attack surface: md4 / md5 / ripemd128.
Severity: Medium (CVSS 5.3/10). Risk of unauthorized operations or information disclosure.
Update to 8.0.13.
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 'symfony/mailomat-mailer' . 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 'symfony/mailomat-mailer' . | 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
symfony/mailomat-mailer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 symfony/mailomat-mailer to 8.0.13ステージング環境で 8.0.13 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。
-
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。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-48747 symfony Fixed in: 7.4.13+dfsg-1
- Ubuntu UBUNTU-CVE-2026-48747 symfony
References
- advisory github.com
- advisory github.com
- advisory nvd.nist.gov
- package github.com
- patch github.com
- web github.com
- web github.com
- web symfony.com
- web github.com
- web github.com
- web github.com