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2 vulnerabilities found for libass by libass

CVE-2026-61627 (GCVE-0-2026-61627)
Vulnerability from cvelistv5
Published
2026-10-30 14:55
Modified
2026-10-30 15:51
Severity ?
7.3 (High) - CVSS:4.0/AV:L/AC:H/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CWE
Summary
libass is a portable subtitle renderer for the `ASS`/SSA (Advanced Substation Alpha/Substation Alpha) subtitle format. Prior to 0.17.5, libass can overread and overwrite the glyph array in `wrap_lines_measure` while rendering malicious `ASS` content. In `wrap modes other than two`, a final line ending with a literal backslash-n sequence and otherwise consisting only of such sequences or spaces can remain after early trimming and make the line-measurement loops overshoot by one glyph. When the total text size exactly matches the allocated glyph-array capacity, the first loop reads an uninitialized 32-bit fixed-point `pos.x` value, although that value is not subsequently used. The second loop writes `pos.x` and `pos.y` beyond the array, zeroing the first and adding an attacker-controllable offset to the second. No actual exploitation beyond possible denial of service is known; broader exploitation is theoretical and constrained by the addresses, limited writes, and ASLR. This issue is fixed in version 0.17.5.
References
Impacted products
Vendor Product Version
libass libass Version: < 0.17.5
 Create a notification for this product.
Show details on NVD website

To clipboard 

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CVE-2026-61626 (GCVE-0-2026-61626)
Vulnerability from cvelistv5
Published
2026-10-30 14:52
Modified
2026-11-04 22:45
Severity ?
7.3 (High) - CVSS:4.0/AV:L/AC:H/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CWE
Summary
libass is a portable subtitle renderer for the ASS/SSA (Advanced Substation Alpha/Substation Alpha) subtitle format. From 0.17.4 until 0.17.5, libass event pruning does not guard negative Matroska `ReadOrder` values, allowing an attacker to clear arbitrarily many bits to zero at attacker-controlled positions near the NULL pointer. Exploitation requires a malicious Matroska stream loaded through `ass_process_chunk`, enabled read-order checking, and later pruning of the malicious events. Read-order checking is enabled by default unless `ass_set_check_readorder` is called with zero; pruning must occur explicitly through `ass_prune_events` or through automatic pruning previously enabled with `ass_configure_prune`. On common systems with arithmetic right shift, 32-bit int values, the upper address region reserved to the kernel, and matching binary/kernel architecture, the expected consequence is denial of service. More extensive exploitation on uncommon systems is theoretical and strongly constrained by the target addresses, bit-clearing-only mutation, and ASLR. This issue is fixed in version 0.17.5.
References
Impacted products
Vendor Product Version
libass libass Version: >= 0.17.4, < 0.17.5
 Create a notification for this product.
Show details on NVD website

To clipboard 

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