CVE-2026-10536
CRITICALCVE-2026-10536 is a critical-severity (CVSS 9.8) Use After Free vulnerability. O3 Security confirms whether CVE-2026-10536 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
HTTP/2 stream-dependency tree UAF
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-10536.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-10536 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 0 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Description
A use-after-free vulnerability exists in libcurl when an application
configures an HTTP/2 stream-dependency tree via CURLOPT_STREAM_DEPENDS or
CURLOPT_STREAM_DEPENDS_E, subsequently invokes curl_easy_reset(), and
finally terminates the handle with curl_easy_cleanup(). During this final
cleanup phase, libcurl attempts to access and modify an internal structure
that was already freed during the reset operation.
Detection & mitigation playbook
VulnerabilityDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for the affected component. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Remediation status
No patched version of the affected component has shipped for CVE-2026-10536 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-10536 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-10536. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
This Moderate impact use-after-free flaw in libcurl can lead to application crashes and Denial of Service. It occurs when an application specifically configures an HTTP/2 stream-dependency tree and then performs a precise sequence of `curl_easy_reset()` and `curl_easy_cleanup()` operations, attempting to access…
Frequently Asked Questions
Is CVE-2026-10536 in your dependencies?
O3 detects CVE-2026-10536 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.