CVE-2026-48691
Publication date 26 May 2026
Last updated 27 May 2026
Ubuntu priority
Description
FastNetMon Community Edition through 1.2.9 contains an integer overflow in the BGP AS_PATH attribute encoder. In src/bgp_protocol.hpp, the IPv4UnicastAnnounce::get_attributes() function computes attribute_length as 'sizeof(bgp_as_path_segment_element_t) + this->as_path_asns.size() * sizeof(uint32_t)' and stores it in a uint8_t field (line 600-605). Since uint8_t can only hold values 0-255, an AS_PATH containing more than 63 ASNs (2 + 64*4 = 258 > 255) causes silent truncation. The truncated length is used for buffer sizing, while the actual data written is the full untruncated amount, resulting in a heap buffer overflow. Similarly, the path_segment_length field at line 621 is also uint8_t, truncating with more than 255 ASNs.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| fastnetmon | 26.04 LTS resolute |
Needs evaluation
|
| 25.10 questing |
Needs evaluation
|
|
| 24.04 LTS noble |
Needs evaluation
|
|
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal |
Needs evaluation
|
|
| 18.04 LTS bionic |
Needs evaluation
|
References
Other references
- https://www.cve.org/CVERecord?id=CVE-2026-48691
- https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48691-bgp-as-path-overflow
- https://github.com/pavel-odintsov/fastnetmon/commit/94c66d5b100c42fb8bd10a22ca595e46895d60d0
- https://github.com/pavel-odintsov/fastnetmon/pull/1054
- https://github.com/pavel-odintsov/fastnetmon
- https://github.com/pavel-odintsov/fastnetmon/blob/master/src/bgp_protocol.hpp