CVE-2026-73261
CVE-2026-73261 · Mongoose: handle_opt() missing opts[1] > len check — 1-byte OOB read corrupts TCP MSS, silences mg_send() per connection
This page contains facts from public vulnerability sources. Check the original advisory before updating.
Mongoose is an embedded web server and network library. Prior to 7.23, the built-in TCP/IP stack enabled by MG_ENABLE_TCPIP in src/net_builtin.c does not reject a TCP option whose declared opts[1] length exceeds the remaining option bytes. In handle_opt(), a NOP followed by a truncated MSS option causes opts[3] to be read outside the declared options area and used as the low byte of dmss. An unauthenticated remote peer can corrupt the per-connection MSS value so later mg_send() calls transmit truncated or zero-length application payloads while the TCP connection otherwise appears healthy. This issue is fixed in version 7.23.
CVSS 7.5 · High · EPSS 0.3% · Fix available
- Published
- Updated
Stack: system
Affected products and versions
mongoose
- Versions
- < 7.23: Affected
No fix published
mongoose Debian:14
- Versions
- 7.21+ds-1
- 7.21+ds-1~bpo13+1
- 7.21+ds-2
- 7.22+ds-1
- 7.22+ds-1~bpo13+1
- 7.23+ds-1~bpo13+1
- Affected ranges
- ECOSYSTEM: < 7.23+ds-1
Update to 7.23+ds-1
mongoose Ubuntu:26.10
- Versions
- 7.21+ds-1
- 7.21+ds-2
- 7.22+ds-1
- 7.23+ds-1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published