CVE-2026-77396 — PJSIP: Heap buffer overflow in the AVI parser
PJSIP is a free and open source multimedia communication library written in C. In 2.17 and earlier, the PJSIP AVI parser in pjmedia/src/pjmedia/avi_player.c uses an input-file video chunk length as the number of bytes copied into a frame buffer whose capacity is derived from the declared media dimensions. A crafted AVI file can therefore cause an attacker-controlled out-of-bounds write past the heap allocation when an application plays the file or pulls its frames. The existing size assertion does not protect production release builds, where assertions are disabled. Typical local playback can crash the process, while applications that accept untrusted AVI sources expose a stronger memory-corruption condition. No fixed version is available as of this review.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- Technical severity (medium)+3
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Pjsip Pjproject).
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- Exploitation requires user interaction: tighten email/web filtering and warn affected users.
- Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 6.9 | CVSS 4.0 | Medium | — | — | security-advisories@github.com via NIST National Vulnerability Database |
| 6.9 | CVSS 4.0 | Medium | — | — | GitHub_M via CVE Program (cve.org) e CISA ADP |
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X (score shown at the top: security-advisories@github.com) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
- Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · pjsip/pjproject
- SSVC assessment updated
- Record published
- CVSS changed · 6.9
- Source status changed · → Undergoing Analysis
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× Official description updated · Oct 15, 2026 – Oct 15, 2026
References
2 on the record
Elsewhere on this site
Related CVEs (same products)
- High CVE-2026-84975 PJSIP: TLS server identity (hostname) verification bypass via embedded NUL in certificate SubjectAltName (OpenSSL and GnuTLS backends) 27d
- Medium CVE-2026-57166 PJSIP: Pre-authentication overflow in the telnet CLI error Sep 4, 2026
- Critical CVE-2026-57162 PJSIP: Stack overflow parsing SDP a=crypto attributes Sep 4, 2026
- High CVE-2026-57161 PJSIP: Stack overflow handling Service-Route headers in a registration response Sep 4, 2026
- Critical CVE-2026-57163 PJSIP: Stack overflow parsing a TLS peer certificate's SubjectAltName in GnuTLS backend Sep 4, 2026
- Medium CVE-2026-57165 PJSIP: Pre-authentication overflow in the telnet CLI history Sep 4, 2026
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No FIRST EPSS score.
- No fixed version, patch or mitigation documented.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-77396 is "PJSIP: Heap buffer overflow in the AVI parser", rated Medium. It affects Pjproject (Pjsip); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 6.9 describes technical severity. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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