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TI-2026-33544 Aliases CVE-2026-45809

OpenSIPS: Denial of Service in watcherinfo XML generation from oversized watcher URI

Priority HIGH 77CWE-121Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-121 and the CVSS impact.

Summary

OpenSIPS is a Session Initiation Protocol (SIP) server implementation. Versions prior to 3.6.6 and 4.0.0-rc1 contain a denial of service vulnerability in the watcherinfo generation functionality. An attacker can create an oversized watcher entry by sending a SUBSCRIBE Event: presence request with a long From URI, and then trigger presence.winfo watcherinfo XML generation for the same presentity. OpenSIPS copies the stored watcher URI into a fixed-size stack buffer, overflowing it and crashing the process. A remote attacker can crash an OpenSIPS worker in deployments that expose handle_subscribe() and allow watcherinfo (presence.winfo) generation. The issue is configuration-dependent because the presence and presence_xml modules must be loaded and SUBSCRIBE routing must be reachable. This issue has been fixed in versions 3.6.6 and 4.0.0-rc1.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00637 50th percentileScored 2026-11-07
Fix Fixed opensips (OpenSIPS): 3.6.6, 4.0.0-rc1

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
OpenSIPSopensips3.4.0 to before 3.6.6; 4.0.0-beta to before 4.0.0-rc13.6.6, 4.0.0-rc1Patch availableCNA
  • opensips VendorOpenSIPS Affected 3.4.0 to before 3.6.6; 4.0.0-beta to before 4.0.0-rc1 Fixed in 3.6.6, 4.0.0-rc1 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:a:opensips:opensips:*:*:*:*:*:*:*:*——OpenSIPS
  • cpe:2.3:a:opensips:opensips:*:*:*:*:*:*:*:* Versions — — ·OpenSIPS

Remediation

  • Fix · CNA opensips (OpenSIPS) Fixed in 3.6.6, 4.0.0-rc1

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-45809
  2. 2026-10-25 EPSS moved to the 50th–90th percentile

References

Other 3

  • TI-2026-33290 OpenSIPS: Stack Buffer Overflow in sip_to_json() Header Name Copy CVSS 3.1CRITICAL 9.8
  • TI-2026-33289 OpenSIPS: Global Buffer Overflow in construct_uri CVSS 3.1CRITICAL 9.1
  • TI-2026-32940 OpenSIPS: Buffer Overflow in Base64 Encode Transformation CVSS 3.1CRITICAL 9.1
  • TI-2026-34055 OpenSIPS: Denial of Service in SDP bandwidth parsing via QoS SDP cloning CVSS 4.0HIGH 8.7
  • TI-2026-32931 OpenSIPS: Denial of service in presence.handle_publish() from unchecked Content-Type state CVSS 4.0HIGH 8.7
  • TI-2026-32942 OpenSIPS: SIP Message Smuggling via TCP Content-Length Integer Overflow CVSS 3.1HIGH 7.5
See all 20 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences