Buffer overflow in Zeromq Libzmq
CVE-2021-20235
There's a flaw in the zeromq server in versions before 4.3.3 in src/decoder_allocators.hpp. The decoder static allocator could have its sized changed, but the buffer would remain the same as it is a static buffer. A remote, unauthenticated attacker who sends a crafted request to the zeromq server could trigger a buffer overflow WRITE of arbitrary data if CURVE/ZAP authentication is not enabled. The greatest impact of this flaw is to application availability, data integrity, and confidentiality.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.439 (98.7th percentile), scored .
Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 99th percentile — 98.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.439 · newest: 0.439 · change: 0.000
Affected products
- Zeromq Libzmq
- Zeromq — versions zeromq 4.3.3
Weakness classification (CWE)
References
- bugzilla.redhat.com/show_bug.cgi (Patch, Third Party Advisory, Issue Tracking)
- github.com/zeromq/libzmq/security/advisories/GHSA-fc3w-qxf5-7hp6 (Patch, Third Party Advisory)
Frequently asked questions
- What is CVE-2021-20235?
- CVE-2021-20235 is a high-severity vulnerability in Zeromq Libzmq, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 8.1/10. Published 2021-04-01.
- How severe is CVE-2021-20235?
- High severity. CVSS v3 base score is 8.1 out of 10.