Vulnerability in OpenSSL
CVE-2026-34183
Issue summary: Remote peer may exhaust heap memory of the QUIC server or client by flooding it with packets containing PATH_CHALLENGE frames. Impact summary: A malicious remote peer can cause an unbounded memory allocation which can lead to an abnormal termination of the application acting as a QUIC client or server and a Denial of Service. A remote peer may exhaust heap memory by flooding the local QUIC stack with PATH_CHALLENGE frames. The local QUIC stack allocates a PATH_RESPONSE frame for every PATH_CHALLENGE it receives. The allocated PATH_RESPONSE frame gets freed only when the remote peer acknowledges reception of the PATH_RESPONSE frame which will not be done by a malicious peer. The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this issue. The QUIC stack is outside of OpenSSL FIPS module boundary.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.010 (62.9th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 63rd percentile — 62.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.010 · newest: 0.010 · change: 0.000
Affected products
- OpenSSL — versions 4.0.0, 3.6.0, 3.5.0
Weakness classification (CWE)
References
- github.com/openssl/security/commit/5b306efb0b3779dfdd0803b4afc9d08c91f11517
- github.com/openssl/security/commit/7d06955ebe0ecf8adfd4c1e92018586da47ef9ac
- github.com/openssl/security/commit/d2e9efbe4900a373227deb136e8665401404ffac
- github.com/openssl/security/commit/fbaa83859c01ad64f497b757aaf51be7d05ed9eb
- openssl-library.org/news/secadv/20260609.txt (vendor-advisory, Vendor Advisory)
- github.com/openssl/openssl/commit/5b306efb0b3779dfdd0803b4afc9d08c91f11517 (Patch, patch)
- github.com/openssl/openssl/commit/7d06955ebe0ecf8adfd4c1e92018586da47ef9ac (Patch, patch)
- github.com/openssl/openssl/commit/d2e9efbe4900a373227deb136e8665401404ffac (Patch, patch)
- github.com/openssl/openssl/commit/fbaa83859c01ad64f497b757aaf51be7d05ed9eb (Patch, patch)
Frequently asked questions
- What is CVE-2026-34183?
- CVE-2026-34183 is a high-severity vulnerability in OpenSSL, classified under CWE-1325. CVSS score: 7.5/10. Published 2026-06-09.
- How severe is CVE-2026-34183?
- High severity. CVSS v3 base score is 7.5 out of 10.