CVE-2026-73324
CVE-2026-73324 — VLC media player 3.0.0 through 3.0.23 Heap Out-of-Bounds Read via Unterminated RealRTSP Response Line
VLC media player copies an RTSP response line into a fixed buffer without guaranteeing termination and then treats that buffer as a C string. RtspReadLine in modules/access/rtsp/access.c calls strncpy with the full buffer length, which writes no terminator when the source line is at least as long as the destination, and rtsp_get in modules/access/rtsp/rtsp.c allocates that buffer as BUF_SIZE bytes and passes it to strdup. When a server returns a line of 4096 bytes or more, strdup measures its length past the end of the allocation and copies adjacent heap bytes until an incidental zero byte. Because the affected line is the Session header, the disclosed bytes are retained as the session identifier and sent back to the server on every subsequent request, so the operator of a hostile server reads heap memory from the client rather than inferring it. The attacker controls the line length and therefore how far the read runs. A single playlist entry naming a realrtsp URL is sufficient. The module is a build-time option, disabled in some distribution packages and enabled in the official VideoLAN builds.
Published Updated Sources: NVD, VideoLAN (CNA), GitHub, SOCRadar CTI
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.
Exploitation
Unreported
no source claims exploitation
EPSS
0%
ahead of 0% of scored CVEs
CVSS base
6.5
medium · 2 sources
Remediation
The vendor's own words where we have them.
Upgrade VLC media player to a fixed release. Apply vendor patches per advisory and restrict external exposure of the affected component until patched.
First 24 hours
Ordered from the record's own fields — exposure first, because you cannot patch what you have not found.
- Identify exposed assets running affected vendor/product/version combinations.
- Prioritize based on EPSS, PoC availability, and external exposure.
- Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class.
Affected scope
Vendor, product and version as the advisories word them.
| Vendor | Product | Versions | Status |
|---|---|---|---|
| VideoLAN | VLC media player | 3.0.0 to <= 3.0.23 | Vulnerable |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Availability
None
Confidentiality
High
Integrity
None
Scope
Unchanged
Attack Complexity
Low
Attack Vector
Network
Privileges Req
None
User Interaction
Required
Every base score collected
Sources score independently and disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Source |
|---|---|---|---|---|---|
| 6.5 | CVSS 3.1 | medium | 2.8 | 3.6 | NVD, VideoLAN (CNA) |
| 6.9 | CVSS 4.0 | medium | — | — | VideoLAN (CNA) |
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
What this weakness leads to
MITRE's own consequences and mitigations for the weakness class — the authority's wording, not guidance derived from the CVSS vector.
CWE-170 · Improper Null Termination
- Read Memory
- Execute Unauthorized Code or Commands
- DoS: Crash, Exit, or Restart
- DoS: Resource Consumption (CPU)
Mitigation: Use a language that is not susceptible to these issues. However, be careful of null byte interaction errors (CWE-626) with lower-level constructs that may be written in a language that is susceptible.
CWE-125 · Out-of-bounds Read
- Read Memory
- Bypass Protection Mechanism
Mitigation: Assume all input is malicious. Use an accept known good input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, boat may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as red or blue. Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright. To reduce the likelihood of introducing an out-of-bounds read, ensure that you validate and ensure correct calculations for any length argument, buffer size calculation, or offset. Be especially careful of relying on a sentinel (i.e. special character such as NUL) in untrusted inputs.
Weakness & attack patterns
- CWE-125Out-of-bounds Read
- CWE-170
Attack patterns reported against this CVE. The ATT&CK techniques below are inferred from its weakness class.
Detection
Read off the CVSS vector and the weakness class. Starting points, not rules we have tested.
- Search application, proxy, and WAF logs for requests touching /access/rtsp/access.c, /access/rtsp/rtsp.c.
- Prioritize edge telemetry for network-reachable VLC media player.
Timeline
What happened to this CVE, newest first — with the readings a source repeats on a schedule counted underneath rather than listed.
- 2026
Added · CVSS 3.1 6.5 (AV:N)
Sep 9, 2026 · NVD
Initial · CVE published
Sep 9, 2026 · NVD
CVE published by MITRE.
Sep 9, 2026 · SOCRadar CTI
References
4 on the record
- github.com/videolan/vlc
Exploit, Third Party Advisory
- github.com/videolan/vlc/blob/3.0.23/modules/access/rtsp/access.c
Exploit, Third Party Advisory
- github.com/videolan/vlc/blob/3.0.23/modules/access/rtsp/rtsp.c
Exploit, Third Party Advisory
- www.vulncheck.com/advisories/vlc-media-player-3.0.0-through-3.0.23-heap-out-of-bounds-read-via-unterminated-realrtsp-response-line
Vendor Advisory, Mitre
Elsewhere on this site
- VideoLANevery CVE for this vendor
- Memory Corruptionsame class
- CWE-125other pages naming this weakness
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 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 record1
What should defenders know first?
CVE-2026-73324 is VLC media player 3.0.0 through 3.0.23 Heap Out-of-Bounds Read via Unterminated RealRTSP Response Line, a medium vulnerability affecting VLC media player from VideoLAN. The current evidence does not list it in CISA KEV, and the exploit status is: Active exploitation is not confirmed from current sources for CVE-2026-73324. Public exploit evidence is: A public PoC is not confirmed from current sources for CVE-2026-73324. The affected-version evidence is listed in the key facts and affected products tables. Defenders should first verify whether exposed or business-critical assets run those versions, then apply vendor patches or mitigations, restrict reachable attack surface, and preserve logs for detection review. CVSS 6.5 describes technical severity, while EPSS 0% helps estimate near-term exploit likelihood; neither replaces asset context. Unknown fields should remain explicit in tickets, and threat actor, IOC, victimology, or payload claims should not be added unless a cited source supports them. Monitor CISA KEV, vendor advisories, NVD changes, public PoC repositories, and internal telemetry for update triggers.