Unsafe Deserialization in symfony/monolog-bridge (CVE-2026-45077)
Summary
Vulnerability in symfony/monolog-bridge (CVE-2026-45077). Risk of unauthorized operations or information disclosure. Exploitable via allowed_classes. Mitigation: upgrade to 8.0.12 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 5.4.52, 6.4.40, 7.4.12, and 8.0.12, the server:log listener (Symfony\Bridge\Monolog\Command\ServerLogCommand) binds to 0.0.0.0:9911 by default and processes each received frame with unserialize(base64_decode($message)) without authentication, integrity checks, or an allowed_classes allowlist, allowing any reachable host to submit attacker-chosen serialized PHP payloads that can crash the listener and may trigger object-injection gadget effects. This issue is fixed in versions 5.4.52, 6.4.40, 7.4.12, and 8.0.12.
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-2026-45077 has been found in symfony/monolog-bridge.
Attackers can target a specific entry point like allowed_classes over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 8.6/10.
What to do: upgrade symfony/monolog-bridge to 8.0.12 or later.
If unsure, ask your IT team or search "symfony/monolog-bridge CVE-2026-45077" on the vendor's site.
CVE-2026-45077 (symfony/monolog-bridge) — CWE-502 / CVSS v3 8.6
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: allowed_classes
Patched: 8.0.12 — 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.
Unsafe deserialization (CWE-502) exists in symfony/monolog-bridge. Attackers reach the vulnerable code path via allowed_classes without authentication.
Check the vendor advisory for the affected versions of symfony/monolog-bridge. Attack surface: allowed_classes.
Severity: High (CVSS 8.6/10). Risk of unauthorized operations or information disclosure.
Update to 8.0.12.
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/monolog-bridge' . 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/monolog-bridge' . | 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/monolog-bridge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/monolog-bridge to 8.0.12ステージング環境で 8.0.12 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-2026-45077 symfony
- Ubuntu UBUNTU-CVE-2026-45077 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
- web github.com
- web github.com