CVE-2026-26203
Received Received - Intake
Heap Buffer Underflow in PJSIP H.264 Packetizer Prior to

Publication date: 2026-02-19

Last updated on: 2026-02-20

Assigner: GitHub, Inc.

Description
PJSIP is a free and open source multimedia communication library. Versions prior to 2.17 have a critical heap buffer underflow vulnerability in PJSIP's H.264 packetizer. The bug occurs when processing malformed H.264 bitstreams without NAL unit start codes, where the packetizer performs unchecked pointer arithmetic that can read from memory located before the allocated buffer. Version 2.17 contains a patch for the issue.
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Meta Information
Published
2026-02-19
Last Modified
2026-02-20
Generated
2026-06-16
AI Q&A
2026-02-19
EPSS Evaluated
2026-06-15
NVD
CVE-2026-26203
EUVD
EUVD-2026-7974
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
pjsip pjsip to 2.17 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-416 The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
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Executive Summary

This vulnerability exists in PJSIP, an open source multimedia communication library, specifically in versions prior to 2.17. It is a critical heap buffer underflow issue in the H.264 packetizer component. The problem occurs when the packetizer processes malformed H.264 bitstreams that lack NAL unit start codes. In this scenario, the packetizer performs unchecked pointer arithmetic, which can cause it to read memory located before the allocated buffer.

Impact Analysis

The vulnerability can lead to reading memory outside the intended buffer boundaries, which may cause undefined behavior such as application crashes or potentially allow attackers to access sensitive information or execute arbitrary code. Since it is a heap buffer underflow, it can compromise the stability and security of applications using affected versions of PJSIP.

Compliance Impact

I don't know

Detection Guidance

I don't know

Mitigation Strategies

To mitigate this vulnerability, upgrade PJSIP to version 2.17 or later, as this version contains a patch that fixes the critical heap buffer underflow issue in the H.264 packetizer.

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