Vulnerability in soupsieve (CVE-2026-49477)
Summary
Vulnerability in soupsieve (CVE-2026-49477). Risk of unauthorized operations or information disclosure. Exploitable via VALUE. Mitigation: upgrade to 2.8.4 or later.
Original description
The description as published by the source.
Soup Sieve is a CSS selector library designed to be used with Beautiful Soup 4. Prior to 2.8.4, the CSS selector parser in soupsieve contains a regular expression vulnerable to catastrophic backtracking when processing an attribute selector with an unterminated quoted value in soupsieve/css_parser.py, allowing an attacker who can supply untrusted CSS selector strings to soupsieve.compile() or Beautiful Soup .select() / .select_one() to cause CPU exhaustion and denial of service. This issue is fixed in version 2.8.4.
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-2026-49477 has been found in soupsieve.
Attackers can target a specific entry point like VALUE over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade soupsieve to 2.8.4 or later.
If unsure, ask your IT team or search "soupsieve CVE-2026-49477" on the vendor's site.
CVE-2026-49477 (soupsieve) — CWE-400 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: VALUE / css_parser.py / RE_VALUES / beautifulsoup4
Patched: 2.8.4 — 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-400) exists in soupsieve. Attackers reach the vulnerable code path via VALUE without authentication.
Check the vendor advisory for the affected versions of soupsieve. Attack surface: VALUE / css_parser.py / RE_VALUES / beautifulsoup4.
Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.
Update to 2.8.4.
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 'soupsieve' . 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 'soupsieve' . | 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
soupsieve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 soupsieve to 2.8.4ステージング環境で 2.8.4 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-2026-49477 soupsieve
- Ubuntu UBUNTU-CVE-2026-49477 soupsieve
References
- advisory github.com
- advisory github.com
- advisory nvd.nist.gov
- patch github.com
- web github.com
- web github.com