CVE-2026-12043
RCE via crafted HTTP/2 HEADERS frames in aws-c-http
Is CVE-2026-12043 being exploited?
Not confirmed. CVE-2026-12043 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.35% probability of exploitation in the next 30 days.
How severe is CVE-2026-12043?
CVE-2026-12043 is rated High with a CVSS score of 8.7. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-12043?
Yes. A fix has been recorded for CVE-2026-12043. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-12043 affect?
CVE-2026-12043 affects aws-c-http (AWS Common Runtime). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-12043?
Upgrade to aws-c-http 0.11.0
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remotely exploitable by a server; memory corruption on client apps via HTTP/2 HEADERS frames, potential code execution.
Patch when possible
- affected>= 0.4.22 and <= 0.10.15
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.