CVE-2026-26203
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
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| pjsip | pjsip | to 2.17 (exc) |
Helpful Resources
Exploitability
| 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 Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
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.
How can this vulnerability impact me? :
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.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
I don't know
How can this vulnerability be detected on my network or system? Can you suggest some commands?
I don't know
What immediate steps should I take to mitigate this vulnerability?
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.