# CVE-2026-121943: Irontec sngrep through 1.9.0 Out-of-Bounds Stack Read via sip_check_packet


- **Severity:** Medium 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`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 4 Nov 2026
- **Updated:** 4 Nov 2026
- **Also known as:** DEBIAN-CVE-2026-121943, GHSA-v6rr-x6vh-q7q4, UBUNTU-CVE-2026-121943

## What is CVE-2026-121943?

CVE-2026-121943 is a medium-severity vulnerability in irontec sngrep, published on 4 Nov 2026. 

### Official description

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.

Weakness: CWE-170 (Improper Null Termination)

## Which versions are affected by CVE-2026-121943?


## How do I fix CVE-2026-121943?

No fix has been published for CVE-2026-121943 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-121943 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-121943 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-121943 and fix it if it is affected.

What it is: CVE-2026-121943 is a medium-severity vulnerability in irontec sngrep, published on 4 Nov 2026. 
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-121943 exists.

Affected product: irontec sngrep. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-121943/ (Markdown: https://insights.sbomify.com/CVE-2026-121943/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-121943
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-121943
- OSV: https://osv.dev/vulnerability/CVE-2026-121943

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-121943/
Summaries are generated and may contain mistakes; the official description above is the record.