CVE-2026-12043
CVE-2026-12043 is a high-severity vulnerability with a CVSS 3.x base score of 8.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-415.
Key facts
- Severity: High (CVSS 3.x base score 8.8)
- CVSS v4: 8.7
- EPSS exploit prediction: 0% (27th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-36541
- Weakness: CWE-415
- Published:
- Last modified:
Description
Improper handling of HPACK dynamic table size updates in the AWS Common Runtime aws-c-http library might allow a remote threat actor operating a server to cause memory corruption on a connecting client application, potentially leading to arbitrary code execution, via a crafted sequence of HTTP/2 HEADERS frames. To remediate this issue, users should upgrade to aws-c-http version 0.11.0.
Frequently asked questions
- What is CVE-2026-12043?
- Improper handling of HPACK dynamic table size updates in the AWS Common Runtime aws-c-http library might allow a remote threat actor operating a server to cause memory corruption on a connecting client application, potentially leading to arbitrary code execution, via a crafted sequence of HTTP/2 HEADERS frames. To remediate this issue, users should upgrade to aws-c-http version 0.11.0.
- How severe is CVE-2026-12043?
- CVE-2026-12043 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
- Is CVE-2026-12043 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (27th percentile), an estimate of the probability of exploitation in the next 30 days.
- How do I fix CVE-2026-12043?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- Does CVE-2026-12043 have an EU (EUVD) identifier?
- Yes. CVE-2026-12043 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-36541.
- When was CVE-2026-12043 published?
- CVE-2026-12043 was published on 2026-06-12 and last updated on 2026-06-17.
References
- https://aws.amazon.com/security/security-bulletins/2026-043-aws/
- https://github.com/awslabs/aws-c-http/releases/tag/v0.11.0
- https://github.com/awslabs/aws-c-http/security/advisories/GHSA-rmjr-3qpm-vh98
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