Information Disclosure in curl (CVE-2021-22898, CVSS 3.1)

Summary

Vulnerability in curl (CVE-2021-22898). Risk of unauthorized operations or information disclosure. Exploitable via CURLOPT_TELNETOPTIONS.

Original description

The description as published by the source.

curl 7.7 through 7.76.1 suffers from an information disclosure when the -t command line option, known as CURLOPT_TELNETOPTIONS in libcurl, is used to send variable=content pairs to TELNET servers. Due to a flaw in the option parser for sending NEW_ENV variables, libcurl could be made to pass on uninitialized data from a stack based buffer to the server, resulting in potentially revealing sensitive internal information to the server using a clear-text network protocol.

Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV

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-2021-22898 has been found in curl.
Attackers can target a specific entry point like CURLOPT_TELNETOPTIONS over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 3.1/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "curl CVE-2021-22898" on the vendor's site.

CVE-2021-22898 (curl) — CWE-200 / CVSS v3 3.1
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: CURLOPT_TELNETOPTIONS
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.

❓ What is the problem

Information disclosure (CWE-200) exists in curl. Attackers reach the vulnerable code path via CURLOPT_TELNETOPTIONS without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of curl. Attack surface: CURLOPT_TELNETOPTIONS.

🔥 Severity

Severity: Low (CVSS 3.1/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to the patched release per vendor advisory.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'curl' . 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

1
Identify exposure identify
```
grep -r 'curl' . | 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 curl を grep し、稼働しているサービス・バージョンを把握する。
2
Post-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。

Fix status by distribution

Fixed packages published by each distribution for this CVE

Alpine Linux ALPINE-CVE-2021-22898 curl Fixed in: 7.66.0-r4
Debian DEBIAN-CVE-2021-22898 curl Fixed in: 7.79.1-1

Information Disclosure in curl (CVE-2021-22898)

Summary

Original description

Auto-generated summary

Response actions

Fix status by distribution

References