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Fencer Intel
medium 4.8

CVE-2026-121943 json

Irontec sngrep through 1.9.0 Out-of-Bounds Stack Read via sip_check_packet

published 5d ago modified 5d ago also EUVD-2026-116900

cvss
4.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
5.6%
EPSS 5.6% chance of exploitation in 30 days, percentile 92%
public exploits
0
none known

Summary

Irontec sngrep through 1.9.0 contains an out-of-bounds stack read vulnerability in sip_check_packet and sip_validate_packet caused by an off-by-one length check on 10240-byte SIP payloads. Remote attackers can send a crafted UDP or TCP SIP packet or supply a pcap file to crash sngrep or leak adjacent stack bytes into displayed SIP fields.

Is CVE-2026-121943 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-121943 updated cvss 4.8

sngrep: sngrep: Denial of Service via crafted SIP packet

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
5d ago

Exploit prediction

5.55% chance of exploitation in the next 30 days, higher than 92% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • hackmd.io https://hackmd.io/@haindpwn/cve-2026-121943-121944-sngrep-sip-payload-missing-nul-oob-read referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 6.3 CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N
CNA 3.1 4.8 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L
CNA 4.0 6.3 CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:N/VA:L/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

Affected products

  • irontec sngrep

Classification

Weakness
  • CWE-170 Improper Null Termination

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.