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CVE-2026-61627

libass: Out-of-bounds read and write in wrap_lines_measure

CVSS score

7.3

EPSS probability

—

Risk score

0.7

Published

2 h ago

Official patch verified

Etkilenen ürün ve sürüm için yayımlanan güvenlik güncellemesini uygulayın.

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Vulnerability description

DayBreach AI Explanation

Verified against sources

libass Out-of-bounds Read and Write Vulnerability (CVE-2026-61627)

Sources read

1

Source agreement

Tam uyum

Evidence confidence

%55

Short explanation

libass contains an out-of-bounds read and write vulnerability in wrap_lines_measure while rendering malicious ASS subtitle content.

Why does it matter?

This vulnerability matters because it can lead to memory corruption and potential denial of service conditions, compromising application stability.

What should be done?

  • Upgrade to version 0.17.5 or later.
  • Follow vendor advisory guidance.
  • Restrict processing of untrusted subtitle files.
Chain of evidence and sources2 verified claims

libass, 0.17.5 öncesi sürümlerde wrap_lines_measure içinde sınır dışı okuma ve yazma işlemlerine açıktır.

Aktif istismar bilinmemekte olup daha geniş kapsamlı istismar teorik ve kısıtlıdır.

Show the technical text from the sources

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.

CVSS vector: 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: CWE-125, CWE-787

This explanation was compiled automatically from the source records. Scores, active exploitation, patch and exploit status come straight from the sources.

IMPACT: Affected Products and Software

Affected Products

The following products are affected by CVE-2026-61627 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.

IDVENDORPRODUCTACTION
1libasslibass View
2Ubuntulibass (upstream) View
3Ubuntulibass (xenial) View
4Ubuntulibass (stonking) View
5Ubuntulibass (bionic) View
6Ubuntulibass (focal) View
7Ubuntulibass (jammy) View
8Ubuntulibass (trusty) View
9Ubuntulibass (noble) View
10Ubuntulibass (resolute) View
Total affected vendors: 2|Products: 10

RED HAT CSAF/VEX: Product Impact Check

Red Hat has not yet published a CSAF/VEX impact record for this CVE. This does not mean “not affected”.

SCORING: CVSS from Multiple Sources

CVSS Scores

The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.

SCOREVERSIONSEVERITYVECTORSOURCE
7.3CVSS V40HIGHCVSS:4.0/AV:L/AC:H/AT:N/PR:N/UI:P/VC:H/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:XNVD
7.3CVSS V4_0HIGHCVSS:4.0/AV:L/AC:H/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:NCVE CNA

Patch and Remediation Guide

Solution & Remediation Advisory

Patch verified

4 doğrulanmış yama veya düzeltilmiş sürüm kanıtı bulundu.

ubuntulibass (upstream)1:0.17.5-1

Ubuntu upstream: 1:0.17.5-1

ubuntulibass (noble)1:0.17.1-2ubuntu0.1~esm1

Ubuntu noble: 1:0.17.1-2ubuntu0.1~esm1

ubuntulibass (resolute)1:0.17.4-2ubuntu0.1~esm1

Ubuntu resolute: 1:0.17.4-2ubuntu0.1~esm1

ubuntu

libass vulnerabilities

Open source
Confirm the affected product and version against the source evidence above.
Restrict access to internet-facing services and apply network segmentation.
Apply the official update named in the evidence only to the matching product and version.
Monitor server logs and network endpoints for signs of anomalous execution.

Public exploit and active exploitation status

Verified exploit intelligence

No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.

Weakness Classification and Attack Patterns (CWE & CAPEC)

CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-61627 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-61627 weaknesses.

Attack Vector and Accessibility

ExposureYerel erişim
PermissionsGerekmiyor
User—

Official Sources and Advisories

CVSS Vector Radar Chart

7.3 / 10
Attack VectorLocalComplexityHighPrivilegesNoneUser Interact.RequiredConfidentialityHighIntegrityNoneAvailabilityHigh

Vulnerability Scoring Details

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
Attack VectorLocal
Attack ComplexityHigh
Privileges RequiredNone required
User InteractionP
Confidentiality (Gizlilik)High
Integrity (Bütünlük)P
Availability (Erişilebilirlik)High

Yama doğrulandı

4 doğrulanmış yama veya düzeltilmiş sürüm kanıtı bulundu.

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Weakness Type (CWE & CAPEC)

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CVE-2026-61627 · libass: Out-of-bounds read and write in…