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Response snapshot Oct 29, 2026, 02:31 UTC

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VulnerabilityCVE-2026-116582

Seroval: Script injection through RegExp sources in serialized output

seroval writes a RegExp as a regular expression literal. In affected versions, the element that the serialized output is placed in, and run script in the page. seroval escapes element. RegExp sources did not get the same escaping: - Versions before 1.0.0 wrote the source as is. - Version 1.5.

At a glance

Exploited
Not known
Severity
4.7 Medium (CVSS 3.1)
Chance of exploitation
0.2% in the next 30 days
Sources
1 source

What to do

GitHub lists first patched versions: seroval: 1.6.10; seroval: 1.0.0. Confirm the affected range and upgrade guidance in the exact advisory.

Read GitHub-reviewed advisory GHSA-9wx9-5pv9-3349 (opens a new tab)

What happened

Summary

seroval writes a RegExp as a regular expression literal. In affected versions, the element that the serialized output is placed in, and run script in the page.

Details

seroval escapes element. RegExp sources did not get the same escaping:

Continue reading

- Versions before 1.0.0 wrote the source as is. - Version 1.5.5 stopped escaping element, as server rendering usually does.

In that case an attacker can run script in the page of any user who receives that output.

Patches

Fixed in 1.6.10. A RegExp whose source contains < is now written with the RegExp constructor and an escaped string source. Named groups and lookbehinds keep working.

Workarounds

If you cannot upgrade:

- Do not serialize a RegExp built from untrusted pattern syntax. Send its source and flags as strings, and build the RegExp on the client. - Or reject patterns that contain < before they reach the serializer.

Affected package ranges reported by GitHub: seroval: >= 1.5.5, < 1.6.10 seroval: < 1.0.0

Scores and how they were measured

CVSS base severity

4.7

Version 3.1As of

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

0.2%

Scored Percentile 8.4%

Model and measurement source (opens a new tab)

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    GitHub-reviewed advisory GHSA-9wx9-5pv9-3349 (opens a new tab)

    The public advisory supplies the description, affected package/version ranges, and any listed CVSS metric. GitHub review is not local review.

    Published Checked

  2. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-9wx9-5pv9-3349, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  3. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-116582, scored 2026-10-28. This is a model estimate, not proof of exposure.

    Published Checked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 28). Seroval: Script injection through RegExp sources in serialized output (CVE-2026-116582). https://kevwire.com/record/CVE-2026-116582

MLA

"Seroval: Script injection through RegExp sources in serialized output (CVE-2026-116582)." KEVWire, 28 Oct. 2026, kevwire.com/record/CVE-2026-116582.

Chicago

KEVWire. "Seroval: Script injection through RegExp sources in serialized output (CVE-2026-116582)." Last modified October 28, 2026. https://kevwire.com/record/CVE-2026-116582.

Evidence summary (plain text)

Seroval: Script injection through RegExp sources in serialized output (Oct 28, 2026).
seroval writes a RegExp as a regular expression literal. In affected versions, the   element that the serialized output is placed in, and run script in the page.

seroval escapes   element. RegExp sources did not get the same escaping:

- Versions before 1.0.0 wrote the source as is.
- Version 1.5.5 stopped escaping   element, as server rendering usually does.

In that case an attacker can run script in the page of any user who receives that output.

Fixed in 1.6.10. A RegExp whose source contains < is now written with the RegExp constructor and an escaped string source.
CVSS 4.7 (version 3.1; evidence as of Oct 28, 2026; https://github.com/advisories/GHSA-9wx9-5pv9-3349).
EPSS 0.2% for the following 30 days, scored Oct 28, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-116582&date=2026-10-28).
Sources:
GitHub-reviewed advisory GHSA-9wx9-5pv9-3349: https://github.com/advisories/GHSA-9wx9-5pv9-3349
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2026-116582&date=2026-10-28
Record ID: CVE-2026-116582.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 29, 2026, 02:16 UTC. Ingestion is not an independent editorial investigation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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