CVE-2026-29078CWE-191CWE-787

Integer Underflow in Lexbor ISO‑2022‑JP Encoder

High · published March 13, 2026

CVSS v4.0
8.2
EPSS
0%
Percentile
40.3
In the wild
Unconfirmed
What it is

Lexbor is a web browser engine library. Prior to 2.7.0, the ISO‑2022‑JP encoder in Lexbor fails to reset the temporary size variable between iterations. The statement ctx->buffer_used -= size with a stale size = 3 causes an integer underflow that wraps to SIZE_MAX. Afterwards, memcpy is called with a negative length, leading to an out‑of‑bounds read from the stack and an out‑of‑bounds write to the heap. The source data is partially controllable via the contents of the DOM tree. This vulnerability is fixed in 2.7.0.

The record
Technical detail
CVSS v4.0
8.2 · HIGH
Vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
EPSS
0.00478 · 40.3th percentile
Weaknesses
CWE-191 · Integer Underflow (Wrap or Wraparound); CWE-787 · Out-of-bounds Write
Published
2026-03-13T17:18Z
EPSS history
Timeline
  • 13 MAR 17:18Z
    Integer Underflow in Lexbor ISO‑2022‑JP Encoder
    cvelistv5