CVE-2026-45538

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.8 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5%, top 60% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Elevated
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.8Exploit: Elevated riskExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

OpenSIPS is a Session Initiation Protocol (SIP) server implementation. In versions 4.0.0 and prior, processing a SIP message with a header name longer than 255 bytes causes a stack buffer overflow when sip_to_json() is called in the routing script. Function sip_to_json() (modules/sipmsgops/sipmsgops.c) copies SIP header names into a fixed 255-byte stack buffer without bounds checking, performing a memcpy of the full header-name length even though the SIP parser imposes no such limit (a header name can be roughly 65000 bytes). As a result, when a routing script calls sip_to_json(), a SIP message with a header name longer than 255 bytes triggers a stack buffer overflow in which both the length and content of the overwrite are attacker-controlled, corrupting the saved frame pointer and return address. A single unauthenticated UDP packet to the SIP port (5060) can crash the process or, on builds without stack protections, hijack the return address to achieve remote code execution. This affects deployments whose routing script invokes sip_to_json(). This issue was not fixed at the time of publication.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
75(Attend)
EG Risk 75/100SSVC: Attend

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity98% × 45%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
0%
EPSS %ILE
40%
KEV
Not listed

Published

August 4, 2026

Last Modified

August 5, 2026

Advisory Details (1)

Auto-updated Aug 26, 2026
🔬 Proof of concept available. Patch available. Sources: github.
github Patch Available🟡 PoC Available

Stack Buffer Overflow in sip_to_json() Header Name Copy · Advisory · OpenSIPS/opensips · GitHub

https://github.com/OpenSIPS/opensips/security/advisories/GHSA-37wc-5j8j-95x3

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 12× in last 7d / 51× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-08-30 02:06 UTCEG score recompute
  2. 2026-08-30 01:22 UTCEPSS rescore
  3. 2026-08-29 21:44 UTCEG score recompute
  4. 2026-08-28 21:41 UTCEPSS rescore
  5. 2026-08-27 19:57 UTCEG score recompute
  6. 2026-08-27 14:25 UTCEPSS rescore
  7. 2026-08-26 19:09 UTCEG score recompute
  8. 2026-08-26 14:46 UTCEPSS rescore
  9. 2026-08-25 15:35 UTCEG score recompute
  10. 2026-08-25 13:49 UTCEPSS rescore
  11. 2026-08-24 17:41 UTCEG score recompute
  12. 2026-08-24 13:00 UTCEG score recompute
  13. 2026-08-23 01:45 UTCEG score recompute
  14. 2026-08-23 00:19 UTCEPSS rescore
  15. 2026-08-22 03:51 UTCEG score recompute
  16. 2026-08-21 23:49 UTCEPSS rescore
  17. 2026-08-21 01:33 UTCEG score recompute
  18. 2026-08-20 22:55 UTCEPSS rescore
  19. 2026-08-19 18:55 UTCEG score recompute
  20. 2026-08-19 17:04 UTCEPSS rescore
  21. 2026-08-18 15:47 UTCEG score recompute
  22. 2026-08-18 13:48 UTCEPSS rescore
  23. 2026-08-17 15:57 UTCEG score recompute
  24. 2026-08-17 13:47 UTCEPSS rescore
  25. 2026-08-16 18:07 UTCEG score recompute
Show 26 more
  1. 2026-08-16 14:56 UTCEPSS rescore
  2. 2026-08-16 05:01 UTCEG score recompute
  3. 2026-08-16 02:14 UTCEPSS rescore
  4. 2026-08-15 02:49 UTCEG score recompute
  5. 2026-08-15 01:30 UTCEPSS rescore
  6. 2026-08-14 00:37 UTCEG score recompute
  7. 2026-08-13 22:00 UTCEPSS rescore
  8. 2026-08-12 18:00 UTCEG score recompute
  9. 2026-08-12 13:51 UTCEPSS rescore
  10. 2026-08-11 15:47 UTCEG score recompute
  11. 2026-08-11 02:41 UTCEG score recompute
  12. 2026-08-11 00:00 UTCEPSS rescore
  13. 2026-08-09 15:34 UTCEG score recompute
  14. 2026-08-09 13:46 UTCEPSS rescore
  15. 2026-08-08 17:44 UTCEG score recompute
  16. 2026-08-08 16:37 UTCEPSS rescore
  17. 2026-08-07 19:53 UTCEG score recompute
  18. 2026-08-06 17:41 UTCEG score recompute
  19. 2026-08-06 13:47 UTCEPSS rescore
  20. 2026-08-05 19:51 UTCEG score recompute
  21. 2026-08-05 19:17 UTCEPSS rescore
  22. 2026-08-05 15:29 UTCEG score recompute
  23. 2026-08-05 14:37 UTCEG score recompute
  24. 2026-08-04 21:31 UTCEG score recompute
  25. 2026-08-04 21:12 UTCEG score recompute
  26. 2026-08-04 21:10 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-45538?
CVE-2026-45538 is a critical vulnerability published on August 4, 2026. OpenSIPS is a Session Initiation Protocol (SIP) server implementation. In versions 4.0.0 and prior, processing a SIP message with a header name longer than 255 bytes causes a stack buffer overflow when siptojson() is called in the routing script. Function siptojson() (modules/sipmsgops/sipmsgops.c)…
When was CVE-2026-45538 disclosed?
CVE-2026-45538 was first published in the National Vulnerability Database on August 4, 2026, with the most recent update on August 5, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-45538 actively exploited?
CVE-2026-45538 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 60.5% of all scored CVEs.
What is the CVSS score of CVE-2026-45538?
CVE-2026-45538 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-45538?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-45538, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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