---
cve: "CVE-2025-31498"
severity: "HIGH"
cvss: 8.3
epss: "0.6%"
vendor: "c-ares"
kev: false
exploited: false
published: "2025-04-08 13:53:11"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-22T22:17:22+02:00"
---

# CVE-2025-31498

> 8.3 HIGH · 🧪 PoC

## Beschreibung

c-ares is an asynchronous resolver library. From 1.32.3 through 1.34.4, there is a use-after-free in read_answers() when process_answer() may re-enqueue a query either due to a DNS Cookie Failure or when the upstream server does not properly support EDNS, or possibly on TCP queries if the remote closed the connection immediately after a response. If there was an issue trying to put that new transaction on the wire, it would close the connection handle, but read_answers() was still expecting the connection handle to be available to possibly dequeue other responses. In theory a remote attacker might be able to trigger this by flooding the target with ICMP UNREACHABLE packets if they also control the upstream nameserver and can return a result with one of those conditions, this has been untested. Otherwise only a local attacker might be able to change system behavior to make send()/write() return a failure condition. This vulnerability is fixed in 1.34.5.

## CVSS-Vektor

```
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Hoch | good |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |

## Patch verfügbar (OSV)

- d3a507e920e7af18a5efb7f9f1d8044ed4750013 (Commit)

## Referenzen

- <https://github.com/c-ares/c-ares/security/advisories/GHSA-6hxc-62jh-p29v>
- <https://github.com/c-ares/c-ares/pull/821>
- <https://github.com/c-ares/c-ares/commit/29d38719112639d8c0ba910254a3dd4f482ea2d1>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2025-31498) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_