CVE-2021-27137
Stack buffer overflow in DD-WRT UPnP (M-SEARCH) enabling remote exploit or crash.
Is CVE-2021-27137 being exploited?
Yes. CVE-2021-27137 appears in CISA's Known Exploited Vulnerabilities catalog, which means exploitation in the wild has been confirmed and reported. Treat it as active rather than theoretical, and patch it ahead of higher-scoring vulnerabilities that carry no exploitation evidence.
How severe is CVE-2021-27137?
CVE-2021-27137 is rated High. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2021-27137?
Yes. A fix has been recorded for CVE-2021-27137. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2021-27137 affect?
CVE-2021-27137 affects DD-WRT firmware < 45724, Home/SOHO routers running DD-WRT with UPnP enabled. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2021-27137?
Upgrade DD-WRT to 45724+ or disable UPnP until patched
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Unauthenticated remote attacker can trigger stack buffer overflow via UPnP M-SEARCH, leading to remote code execution or denial of service.
Patch when possible
- affected< 45724
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.