Vulnerability in urllib3 (CVE-2026-97687)
Summary
Vulnerability in urllib3 (CVE-2026-97687). Confidential information can be exposed externally. Exploitable via proxy_ssl_context. Mitigation: upgrade to 2.8.0 or later.
Original description
The description as published by the source.
Impact
urllib3 supports configuring TLS independently for an HTTPS proxy and the target server.
proxy_ssl_context, proxy_assert_hostname, and proxy_assert_fingerprint configure the TLS connection to the proxy. ssl_context and the other target-specific TLS parameters configure the connection to the target server.
In urllib3 versions 1.26.0 through 2.7.0, these configurations were not consistently separated. Depending on the proxy mode, urllib3 could:
- Ignore
proxy_ssl_contextand use the target server's SSL context for the TLS connection to an HTTPS forwarding proxy. - Override the HTTPS proxy's certificate-verification policy with the target server's certificate-verification policy.
- Apply target-specific SNI, hostname assertions, certificate fingerprint assertions, or TLS client credentials to the TLS connection to an HTTPS forwarding proxy.
In particular, configuring cert_reqs="CERT_NONE" for a target server could overwrite the verify_mode of the SSL context configured for the HTTPS proxy. This modification occurred in place and persisted on the context object, potentially disabling proxy certificate verification for later connections that reused the same context.
An attacker able to intercept the connection to an HTTPS proxy may be able to impersonate the proxy when the effective proxy TLS configuration disables certificate verification or otherwise accepts the attacker's certificate. This may occur, for example, when the target server's trust o…
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-2026-97687 has been found in urllib3.
Attackers can target a specific entry point like proxy_ssl_context over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 8.1/10.
What to do: upgrade urllib3 to 2.8.0 or later.
If unsure, ask your IT team or search "urllib3 CVE-2026-97687" on the vendor's site.
CVE-2026-97687 (urllib3) — CWE-295 / CVSS v3 8.1
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: proxy_ssl_context / proxy_assert_hostname / proxy_assert_fingerprint / ssl_context
Patched: 2.8.0 — 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-295) exists in urllib3. Attackers reach the vulnerable code path via proxy_ssl_context without authentication.
Check the vendor advisory for the affected versions of urllib3. Attack surface: proxy_ssl_context / proxy_assert_hostname / proxy_assert_fingerprint / ssl_context.
Severity: High (CVSS 8.1/10). Confidential information can be exposed externally.
Update to 2.8.0.
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 'urllib3' . 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 'urllib3' . | 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
urllib3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 urllib3 to 2.8.0ステージング環境で 2.8.0 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
References
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- package pypi.org
- web github.com
- web github.com
- web github.com
- web github.com
- web github.com