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Vulnerabilities

Vulnerability · CVE-2026-29078

Lexbor is a web browser engine library.

Published Mar 13, 2026 · catalog updated Jun 17, 2026 · Lexbor is a web

Check if you run it

No confirmed exploitation is on record for CVE-2026-29078. EPSS is 0.48%. Act only if a listed version of Lexbor is a web is installed.

Severity
High8.2
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.48%
Remediation
Advisory link
Affected products
cpe lexbor/lexbor

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe lexbor/lexborversion unspecified

How to fix CVE-2026-29078

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-29078. EPSS is 0.48%. Act only if a listed version of Lexbor is a web is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-191: Integer Underflow; CWE-787: Out-of-bounds Write. EPSS 0.48%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 13, 2026 · NIST NVD

    Detected

    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

  2. Jun 17, 2026 · NIST NVD

    Updated

    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

Sources

  • CVE.orgVulnerability recordCVE-2026-29078

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-29078

    30-day exploitation probability 0.5%

    first.org
  • NIST NVDVulnerability recordCVE-2026-29078

    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, me

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.