# CVE-2026-13589: seladb PcapPlusPlus Telnet Subnegotiation Packet TelnetLayer.cpp getSubCommand heap-based overflow

> A heap-based buffer overflow in PcapPlusPlus allows remote attackers to execute arbitrary code or cause denial of service via crafted Telnet packets.

- **Severity:** Medium 6.3 (`CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 29 Jun 2026
- **Updated:** 29 Jun 2026
- **Also known as:** GHSA-x5wv-5f96-x49c

## What is CVE-2026-13589?

CVE-2026-13589 is a medium-severity memory corruption vulnerability in seladb PcapPlusPlus, published on 29 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability was identified in seladb PcapPlusPlus 25.05. This affects the function pcpp::TelnetLayer::getSubCommand of the file Packet++/src/TelnetLayer.cpp of the component Telnet Subnegotiation Packet Handler. The manipulation leads to heap-based buffer overflow. The attack can be initiated remotely. The complexity of an attack is rather high. The exploitability is reported as difficult. The exploit is publicly available and might be used. The identifier of the patch is 98e671010bc7c87b95898c22ae289220ae92542b. It is recommended to apply a patch to fix this issue.

Weakness: CWE-122 (Heap-based Buffer Overflow), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2026-13589?


## How do I fix CVE-2026-13589?

Apply the vendor's patch.

## Is CVE-2026-13589 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-13589 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-13589 and fix it if it is affected.

What it is: CVE-2026-13589 is a medium-severity memory corruption vulnerability in seladb PcapPlusPlus, published on 29 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-13589 exists.

Affected product: seladb PcapPlusPlus. 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-2026-13589/ (Markdown: https://insights.sbomify.com/CVE-2026-13589/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-13589
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-13589
- OSV: https://osv.dev/vulnerability/CVE-2026-13589

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-13589/
Summaries are generated and may contain mistakes; the official description above is the record.