Skip to content
Noroxi
CVE-2021-27137· NVD / CVE Program· CNA mitre

An issue was discovered in router/upnp/src/ssdp.c in DD-WRT before 45724.

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).

HighCVSS 8.1 · v3.1KEVWeaponized No fix recorded
Published
Jul 16, 2026
Updated
Jul 22, 2026
EPSS
4.0% · 90th percentile
Follow this CVE

Sign in to follow · You’ll be notified if a followed record enters KEV, gets an exploit or is updated.

Report tools

JSON

Action score

63

This week

Don’t wait for the next maintenance window.

CVSS
32 / 40 · 8.1 / 10
CISA KEV
30 / 30 · Listed
EPSS
1 / 30 · 4.0%

CISA SSVC decision

Exploitation
active
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · mitre
8.1
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Actively exploited in the wild

CISA added this to its Known Exploited Vulnerabilities catalog on Jul 21, 2026. That signals real attacks, not theory.

Remediation deadline for government agencies: Jul 24, 2026.

Affected systems

VendorProduct
dd-wrtdd-wrt

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • dd-wrt dd-wrtbefore 45724

Versions reported by the vendor

Affected version ranges reported by the assigning authority (mitre). Independent of NVD's CPE analysis and usually ahead of it.

  • DD-WRT DD-WRT

    • before 45724affected

Same product

dd-wrt: all records

Other highest-scoring records for the same primary product.

  • CVE-2009-2765httpd.c in httpd in the management GUI in DD-WRT 24 sp1, and other versions before build 12533, allows remote attackers to execute arbitrary
    58Plan
  • CVE-2022-27631A memory corruption vulnerability exists in the httpd unescape functionality of DD-WRT Revision 32270 - Revision 48599.
    39Monitor
  • CVE-2020-13976An issue was discovered in DD-WRT through 16214.
    36Monitor
  • CVE-2012-6297Command Injection vulnerability exists via a CSRF in DD-WRT 24-sp2 from specially crafted configuration values containing shell meta-charact
    36Monitor
  • CVE-2009-2766httpd.c in httpd in the management GUI in DD-WRT 24 sp1 does not require administrative authentication for programs under cgi-bin/, which al
    32Monitor
  • CVE-2008-6975Multiple cross-site request forgery (CSRF) vulnerabilities in apply.cgi in DD-WRT 24 sp2 allow remote attackers to hijack the authentication
    27Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

Weaponized

A ready exploit tool or active in-the-wild use is known for this vulnerability. This should be your top priority.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. CISA KEV+4 d
  3. TodaySep 29, 2026+75 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • Special conditions such as timing or configuration are required.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-121 · Stack-based Buffer Overflow

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Noroxi analysis

No Noroxi analysis for this record yet

We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.

We use this product, ask for help

Change log

No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records