CVE-2026-58049
CVE-2026-58049 is a high-severity vulnerability with a CVSS 3.x base score of 8.6. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-787.
Key facts
- Severity: High (CVSS 3.x base score 8.6)
- CVSS v4: 8.8
- EPSS exploit prediction: 0% (12th percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-787
- Published:
- Last modified:
Description
FFmpeg's RASC video decoder (decode_dlta in libavcodec/rasc.c) performs 32-bit reads and writes at the row cursor before the NEXT_LINE row-boundary check and validates the DLTA region in pixel rather than byte units, so a DLTA run on a PAL8 frame can access several bytes past the row allocation. A crafted media stream using the RASC FourCC, decoded by libavcodec, triggers a bitstream-controlled out-of-bounds heap write and adjacent out-of-bounds read, leading to memory corruption.
Frequently asked questions
- What is CVE-2026-58049?
- FFmpeg's RASC video decoder (decode_dlta in libavcodec/rasc.c) performs 32-bit reads and writes at the row cursor before the NEXT_LINE row-boundary check and validates the DLTA region in pixel rather than byte units, so a DLTA run on a PAL8 frame can access several bytes past the row allocation. A crafted media stream using the RASC FourCC, decoded by libavcodec, triggers a bitstream-controlled out-of-bounds heap write and adjacent out-of-bounds read, leading to memory corruption.
- How severe is CVE-2026-58049?
- CVE-2026-58049 has a CVSS 3.x base score of 8.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability high.
- Is CVE-2026-58049 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (12th percentile), an estimate of the probability of exploitation in the next 30 days.
- How do I fix CVE-2026-58049?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- When was CVE-2026-58049 published?
- CVE-2026-58049 was published on 2026-06-28 and last updated on 2026-07-06.
References
- https://github.com/FFmpeg/FFmpeg/blob/master/libavcodec/rasc.c
- https://github.com/bikini/exploitarium/tree/main/ffmpeg-rasc-dlta-calc-poc
- https://www.vulncheck.com/advisories/ffmpeg-out-of-bounds-write-in-rasc-decoder-decode-dlta
- https://access.redhat.com/security/cve/CVE-2026-58049
- https://bugzilla.redhat.com/show_bug.cgi?id=2493952
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-58049.json
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