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Medium, CVSS 6.5amended

OpenCC has an Out-of-bounds read when processing truncated UTF-8 input

GHSA-7fqq-q52p-2jjg

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (opencc 1.2.0; opencc 1.2.0), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • npm opencc

    Affected
    < 1.2.0
    Fixed in
    1.2.0

  • PyPI opencc

    Affected
    < 1.2.0
    Fixed in
    1.2.0

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
6.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
EPSS
No dated EPSS signal available.
Source description

As published by the source; long descriptions are shortened.

Summary OpenCC versions before 1.2.0 contain two CWE-125: Out-of-bounds Read issues caused by length validation failures in UTF-8 processing. When handling malformed or truncated UTF-8 input, OpenCC trusted derived length values without enforcing the invariant that processed length must not exceed the remaining input buffer. This could result in out-of-bounds reads during segmentation or conversion. Details Two independent code paths in OpenCC failed to enforce the invariant: matchedLength <= remainingLength Both paths assumed derived length values were valid and within input bounds, but did not validate that assumption against the remaining buffer. This created the following failure chain: invalid UTF-8 - incorrect derived length - incorrect pointer advance - remaining-length desynchronization - out-of-bounds read In MaxMatchSegmentation::Segment, this could desynchronize remaining-length tracking and cause out-of-bounds reads during prefix matching. In Conversion::Convert(const…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-7fqq-q52p-2jjg

  2. Revision 1 · created ·

    Published from osv record GHSA-7fqq-q52p-2jjg

Agent brief

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# Patch Next advisory brief: GHSA-7fqq-q52p-2jjg

Advisory: OpenCC has an Out-of-bounds read when processing truncated UTF-8 input
IDs: GHSA-7fqq-q52p-2jjg
Record: https://patchnext.com/advisories/ghsa-7fqq-q52p-2jjg (revision 2, source checked 26 Oct 2026, 12:47 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: opencc 1.2.0; opencc 1.2.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm opencc: affected < 1.2.0; fixed in 1.2.0
- PyPI opencc: affected < 1.2.0; fixed in 1.2.0

## Suggested inspection (read-only)
- `npm ls opencc --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.
- `python -m pip show opencc`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on opencc.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-7fqq-q52p-2jjg (OSV record GHSA-7fqq-q52p-2jjg lists affected ranges: npm opencc >=0 =0 <1.2.0 (fixed))
- Verified: https://github.com/advisories/GHSA-7fqq-q52p-2jjg (GitHub-reviewed advisory GHSA-7fqq-q52p-2jjg lists affected ranges: npm opencc >=0 =0 <1.2.0)

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