CVE-2026-55200
libssh2 - Out-of-Bounds Write via Unchecked packet_length in transport.c
CRITICAL 9.2EPSS 4.0%
libssh2 through 1.11.1, fixed in commit 7acf3df contains an out-of-bounds write vulnerability in ssh2_transport_read() that fails to enforce upper bounds on packet_length field. Remote attackers can send crafted SSH packets with excessively large packet_length values to corrupt heap memory and achieve remote code execution.
- Affected
- libssh2
- CVSS v4.0 VULNCHECK
- 9.2 CRITICAL
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS v3.1 NVD
- 8.3 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L - CVSS v3.1 VULNCHECK
- 8.1 HIGH
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H - EPSS
- 4.02% chance of exploitation in the next 30 days, 90th percentile
- Published
- 2026-06-17
- Updated
- 2026-07-14
Proof-of-concept exploits (12)
- https://web.archive.org/web/20260623211210/https://github.com/bikini/exploitarium/tree/ma…
- 0xBlackash/CVE-2026-5520010★ · 2026-06-23
- xd20111/CVE-2026-552004★ · 2026-06-29
- kaleth4/CVE-2026-552000★ · 2026-07-03
- 0xnhsec/0-day-PoC-Repo19★ · 2026-06-29
- Brandonweisser/expl0★ · 2026-07-09
- Coldtears7/exploitarium0★ · 2026-06-30
- HongKyoungIn/exploitarium-fork0★ · 2026-06-29
- TreasureBoy99/exploitarium0★ · 2026-08-06
- allen-110/exploitarium69★ · 2026-06-29
- vomw/deleted202606270★ · 2026-06-29
- bright77777/mypocs0★ · 2026-09-07
Security advisories
- https://www.vulncheck.com/advisories/libssh2-out-of-bounds-write-via-unchecked-packet-len…
- libssh2/libssh2/pull/2052