// For flags

CVE-2025-31498

c-ares has a use-after-free in read_answers()

Severity Score

8.3
*CVSS v4

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

Track
*SSVC
Descriptions

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.

A flaw was found in c-ares. This vulnerability allows a remote or local attacker to cause a use-after-free, potentially leading to application-level denial of service or other unexpected behavior via manipulation of DNS responses or network conditions during query processing.

It was discovered that c-ares incorrectly handled re-enqueuing certain queries. A remote attacker could possibly use this issue to cause c-ares to crash, resulting in a denial of service.

*Credits: N/A
CVSS Scores
Attack Vector
Network
Attack Complexity
High
Attack Requirements
None
Privileges Required
None
User Interaction
None
System
Vulnerable | Subsequent
Confidentiality
Low
None
Integrity
Low
None
Availability
High
None
Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
High
Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
High
Attack Vector
Network
Attack Complexity
Low
Authentication
None
Confidentiality
None
Integrity
Partial
Availability
Partial
* Common Vulnerability Scoring System
SSVC
  • Decision:Track
Exploitation
None
Automatable
No
Tech. Impact
Partial
* Organization's Worst-case Scenario
Timeline
  • 2025-03-28 CVE Reserved
  • 2025-04-08 CVE Published
  • 2025-04-08 CVE Updated
  • 2025-06-15 EPSS Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
  • CWE-416: Use After Free
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
C-ares
Search vendor "C-ares"
 C-ares
Search vendor "C-ares" for product "C-ares"
 >= 1.32.3 < 1.34.5
Search vendor "C-ares" for product "C-ares" and version " >= 1.32.3 < 1.34.5"
en
Affected