CVE-2026-11586
No exploitation reported by the sources we read.
- Published2026-07-03
- Fixed in8.21.0
- WeaknessCWE-770
Am I affected?
Debian, Ubuntu or Red Hat sometimes backport a fix without changing the upstream version number: such a version reads « to verify », never « affected ».With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.
Description
By default, curl automatically responds to WebSocket PING frames. Because curl lacks an upper bound on memory allocation for unacknowledged frames, a malicious server can exhaust all available memory by flooding curl with rapid, sequential PING messages.
Timeline
dates in UTC- 2026-07-0307:16CVE publishedNVD
Observed activity
isMalicious corpus · updated 2026-10-23 21:37 UTCBlock these indicators
- Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-11586?format=txt
- CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-11586?format=csv
- TAXII collection of exploited CVEs
- The EDL and CSV take an API key on the Pro plan.
Versions per branch
NVD| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 8.x | ≥ 8.16.0, < 8.21.0 | 8.21.0 | NVD |
as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.
Distribution builds and vendor advisories
Packages from OSV.dev and products from the vendors' CSAF advisories.
version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.
Vendor advisories
curl: curl: Denial of Service via WebSocket PING flood
curl as a component of Red Hat Enterprise Linux 6 · curl.src as a component of Red Hat Enterprise Linux 6 · libcurl as a component of Red Hat Enterprise Linux 6 · +5 more
Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update
Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update
Fix
- Update Haxx curl to 8.21.0
- Vendor fix Red Hat Product Security CVE-2026-11586 · 3 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
- Workaround from the vendor Red Hat Product Security CVE-2026-11586 · 15 productsMitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
- No fix planned, says the vendor Red Hat Product Security CVE-2026-11586 · 8 productsOut of support scope
Detection
- Nuclei template
- none so far ProjectDiscovery
- Exploit-DB
- no entry Exploit-DB
- Proof-of-concept repositories
- none listed PoC-in-GitHub
Sources
Technical details
- CVSS v3 Vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Published
- 2026-07-03
- Last Modified
- 2026-09-15
- NVD status
- Modified
Frequently asked questions
What is CVE-2026-11586?
Is CVE-2026-11586 actively exploited?
What is the CVSS score for CVE-2026-11586?
Running curl? Hear about its next vulnerability
Surveillance reads the versions in your stack — a domain, a lockfile or a list — checks each CVE against the ranges its sources publish, and alerts you when one you run is exploited or enters CISA KEV. A version it cannot read stays « version not verified ».
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Go further
- Following what attackers exploit right now? The CISA KEV additions of the month, with their patch deadlines.
- Running this software? Vulnerability monitoring alerts you to new vulnerabilities in your products.
Related vulnerabilities
Same product first, then the same vendor advisory and the same publication week.