DD-WRT 24/24 SP2/45723 UPnP router/upnp/src/ssdp.c strcpy buffer overflow

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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9.5$0-$5k2.09

Summaryinfo

A vulnerability was found in DD-WRT and classified as very critical. Affected by this issue is the function strcpy of the file router/upnp/src/ssdp.c of the component UPnP Handler. Executing a manipulation can lead to buffer overflow. This vulnerability is registered as CVE-2021-27137. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability was found in DD-WRT. It has been declared as very critical. This vulnerability affects the function strcpy of the file router/upnp/src/ssdp.c of the component UPnP Handler. The manipulation with an unknown input leads to a buffer overflow vulnerability. The CWE definition for the vulnerability is CWE-120. The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

An issue was discovered in router/upnp/src/ssdp.c in DD-WRT before 45724. An unsafe strcpy in the UPnP handling functionality allows an unauthenticated remote attacker to send a request that would overflow an internal fixed buffer. Exploitation requires the DD-WRT user to enable UPnP (which is off by default, and only listens on internal interfaces by default). This occurs in ssdp_msearch (reachable by an M-SEARCH request).

The advisory is shared for download at svn.dd-wrt.com. This vulnerability was named CVE-2021-27137 since 02/10/2021. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 07/16/2026).

Upgrading to version 45724 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2021-34854). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 10.0
VulDB Meta Temp Score: 9.5

VulDB Base Score: 10.0
VulDB Temp Score: 9.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Buffer overflow
CWE: CWE-120 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔒

Upgrade: DD-WRT 45724

Timelineinfo

02/10/2021 CVE reserved
07/16/2026 +1981 days Advisory disclosed
07/16/2026 +0 days VulDB entry created
07/16/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: svn.dd-wrt.com
Status: Confirmed

CVE: CVE-2021-27137 (🔒)
GCVE (CVE): GCVE-0-2021-27137
GCVE (VulDB): GCVE-100-379600
EUVD: 🔒

Entryinfo

Created: 07/16/2026 20:13
Updated: 07/16/2026 21:35
Changes: 07/16/2026 20:13 (54), 07/16/2026 21:35 (1)
Complete: 🔍
Cache ID: 216::103

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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