CVE detail
CVE-2026-66035
libssh2 through 1.11.1, fixed in commit 42e33d8, contains a pre-authentication heap buffer overflow vulnerability that allows a malicious SSH server to corrupt heap metadata in any connecting client by sending a packet with a packet_length smaller than the cipher's block size during Encrypt-then-MAC cipher negotiation. In the fullpacket() function in src/transport.c, the ETM path allocates a buffer of packet_length bytes but copies blocksize minus one bytes via memcpy, causing an overflow that on 32-bit glibc writes attacker-controlled bytes into an adjacent chunk's SIZE field, enabling tcache bin confusion, overlapping live objects, and function pointer overwrite during the session handshake before authentication.
Buzz score
Why this CVE is surfacing
This all-time snapshot uses the same composite formula as Trending across a 30-year evidence window, rather than a current rolling window.
Buzz score components · mention 13.9 · diversity 6.5 · KEV 0.0 · OTX 0.0 · PoC 0.0
Why it matters now
Mention timeline
- Total mentions
- 3
- within the 30d window
- Peak daily
- 3
- highest bucket
Evidence
Source links by recency
3 source links · newest first
- https://www.vulncheck.com/advisories/libssh2-heap-buffer-overflow-via-etm-cipher-negotiationwww.vulncheck.com
No excerpt available.
Exploitwww.vulncheck.comJul 24, 2026, 5:17 PM No excerpt available.
Exploitgithub.comJul 24, 2026, 5:17 PMNo excerpt available.
Exploitgithub.comJul 24, 2026, 5:17 PM
Exploit code
Public exploit repository references
Public PoC repositories are third-party, potentially unsafe artifacts. Treat their code as untrusted and use it only on authorized systems in an isolated, least-privilege environment. cvebuzz does not execute the code or verify that an exploit works.
0 repository references · best confidence N/A · max 0 stars
Related records
Similar CVEs
6 related CVEs with shared weakness or product evidence
- CVE-2026-66040CVSS 8.7 · High
FFmpeg through 8.1.2, fixed in commit b506faf, contains a heap out-of-bounds write vulnerability in the native PNG and APNG encoders that allows remote attackers to corrupt heap m…
- CVE-2026-66039CVSS 8.7 · High
FFmpeg through 8.1.2, fixed in commit aafb5c6, contains a signed integer overflow vulnerability in the MACE6 audio decoder that allows attackers to corrupt heap memory by supplyin…
- CVE-2026-66036CVSS 7.7 · High
FFmpeg through 8.1.2, fixed in commit 5d7112c, contains a heap out-of-bounds write vulnerability in the vf_hqdn3d filter that allows attackers to corrupt heap memory by supplying…
- CVE-2026-56392CVSS 1.8 · Low
GNU coreutils unexpand is vulnerable to a heap-based buffer overflow due to an integer overflow during buffer allocation when processing large tab stop (-t) values. The multiplica…
- CVE-2026-56165CVSS 9.8 · Critical
Heap-based buffer overflow in Microsoft Account allows an unauthorized attacker to execute code over a network.
- CVE-2026-49035CVSS 9.2 · Critical
The affected product is vulnerable to a heap-based buffer overflow via a crafted MMS Initiate request. Remote code execution (RCE) has been demonstrated when ASLR is disabled; mem…