CVE-2026-28799Network attack vector

Unauthenticated service crash via premature subscription pool release

Published Mar 6, 2026 · Updated Mar 6, 2026

Heap use-after-free in PJPROJECT before 2.17 allows remote attackers to crash presence servers with an unsubscribe request. During an Expires=0 SUBSCRIBE transaction, on_tsx_state_uas() reports TERMINATED before on_rx_refresh finishes, so the state callback frees status_pool and tmp_pool before pjsip_pres_notify() reuses them. Any unauthenticated SIP peer that can reach a presence UAS supporting presence, MWI, or dialog-event can trigger a process crash and interrupt service.

CVSS severity8.7
High
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap use-after-free in PJPROJECT before 2.17 allows remote attackers to crash presence servers with an unsubscribe request. During an Expires=0 SUBSCRIBE transaction, on_tsx_state_uas() reports TERMINATED before on_rx_refresh finishes, so the state callback frees status_pool and tmp_pool before pjsip_pres_notify() reuses them. Any unauthenticated SIP peer that can reach a presence UAS supporting presence, MWI, or dialog-event can trigger a process crash and interrupt service.

The record

CVE
CVE-2026-28799
Published
Mar 6, 2026
Updated
Mar 6, 2026
Vendor
PJSIP
Product
PJPROJECT
Classifications
CWE-416, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 6, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 6, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 2.17

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

PJSIP · PJPROJECTversion=< 2.17

Published CVSS scores

7.5NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
8.7GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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