# CVE-2026-92387: curl infinite loop via server response omission

Source: https://junglewise.ai/threats/cve-2026-92387-by-permanently-omitting-the-final-control-response-line-a  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-20. Updated: 2026-10-20  
License: CC BY 4.0 with a link back

CVE-2026-92387 · Severity: info · Published 2026-10-20

libcurl is a widely-used library that applications depend on to fetch data over the internet using protocols like FTP, IMAP, POP3, and SMTP. A malicious server can omit the final response line, causing libcurl to enter an infinite loop that blocks all data transfers indefinitely and bypasses timeout protections. While exploitation requires a server feeding data at network speed to keep the client engaged, affected applications could become unresponsive.

Technologies: [Curl](https://junglewise.ai/threats/technologies/curl-curl). Vendors: [Curl](https://junglewise.ai/threats/vendors/curl).

## Quick answers

**Is CVE-2026-92387 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-92387 being exploited in the wild.

**How severe is CVE-2026-92387?** Informational severity, published 20 October 2026.

**Which products and versions are affected?** Curl 8.10.0 to 8.22.0; excludes 8.14.3 in 8.14.x, 8.16.2 in 8.16.x, 8.20.2 in 8.20.x.

**Is there a fix for CVE-2026-92387?** Yes: fixed in 8.23.0, 8.20.2 (8.20.x branch), 8.16.2 (8.16.x branch), 8.14.3 (8.14.x branch). Until then: Avoid using the ping-pong protocols (FTP, IMAP, SMTP, POP3) with libcurl if possible, or upgrade immediately. Note that the curl command-line tool is not affected by this flaw.</anigation>
<parameter name="timeline">[{"kind": "disclosed", "at": "2026-09-11", "note": "Issue reported to curl project"}, {"kind": "patched", "at": "2026-10-14", "note": "curl 8.23.0 released with fix"}, {"kind": "advisory", "at": "2026-10-14", "note": "CVE-2026-92387 published"}] Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-92387 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-92387?** Check whether you run Curl at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in 8.23.0, 8.20.2 (8.20.x branch), 8.16.2 (8.16.x branch), 8.14.3 (8.14.x branch)

Avoid using the ping-pong protocols (FTP, IMAP, SMTP, POP3) with libcurl if possible, or upgrade immediately. Note that the curl command-line tool is not affected by this flaw.</anigation>
<parameter name="timeline">[{"kind": "disclosed", "at": "2026-09-11", "note": "Issue reported to curl project"}, {"kind": "patched", "at": "2026-10-14", "note": "curl 8.23.0 released with fix"}, {"kind": "advisory", "at": "2026-10-14", "note": "CVE-2026-92387 published"}]

## Technical details

The vulnerability is an infinite loop (CWE-835) in libcurl's protocol handlers for FTP, IMAP, POP3, and SMTP. By omitting the final control-response line, a malicious server prevents libcurl from detecting completion and exiting its read loop, bypassing the configured transfer timeout. Exploitation requires network-level conditions (a server maintaining data flow at read speed) but affects all concurrent transfers on the same multi-handle once triggered.

## Affected products

- curl curl 8.10.0 to 8.22.0; excludes 8.14.3 in 8.14.x, 8.16.2 in 8.16.x, 8.20.2 in 8.20.x

## References

- [https://curl.se/docs/CVE-2026-92387.html](https://curl.se/docs/CVE-2026-92387.html)
- [https://curl.se/docs/CVE-2026-92387.json](https://curl.se/docs/CVE-2026-92387.json)

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