JSON::XS versions from 3.0 before 4.05 for Perl read freed stack memory when a FREEZE result's serialisation grows the Perl stack under allow_tags in encode_rv.
With allow_tags, an object's FREEZE method is called in list context and each returned value is encoded through a saved Perl stack pointer. When encoding a returned value calls back into Perl, through TO_JSON under convert_blessed or another FREEZE, and that callback grows the stack, the stack is reallocated while the saved pointer still refers to the freed block.
Encoding such objects reads freed memory, and encode can return undef without an error.
With allow_tags, an object's FREEZE method is called in list context and each returned value is encoded through a saved Perl stack pointer. When encoding a returned value calls back into Perl, through TO_JSON under convert_blessed or another FREEZE, and that callback grows the stack, the stack is reallocated while the saved pointer still refers to the freed block.
Encoding such objects reads freed memory, and encode can return undef without an error.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
|---|---|---|---|---|---|---|---|---|---|
| unaffected |
|
No data.
No data.
No data.
Project Subscriptions
No data.
Advisories
No advisories yet.
Fixes
Solution
Upgrade to JSON-XS 4.05 or later.
Workaround
No workaround given by the vendor.
References
| Link | Providers |
|---|---|
| https://metacpan.org/release/MLEHMANN/JSON-XS-4.05/changes |
|
History
Sat, 14 Nov 2026 12:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | JSON::XS versions from 3.0 before 4.05 for Perl read freed stack memory when a FREEZE result's serialisation grows the Perl stack under allow_tags in encode_rv. With allow_tags, an object's FREEZE method is called in list context and each returned value is encoded through a saved Perl stack pointer. When encoding a returned value calls back into Perl, through TO_JSON under convert_blessed or another FREEZE, and that callback grows the stack, the stack is reallocated while the saved pointer still refers to the freed block. Encoding such objects reads freed memory, and encode can return undef without an error. | |
| Title | JSON::XS versions from 3.0 before 4.05 for Perl read freed stack memory when a FREEZE result's serialisation grows the Perl stack under allow_tags in encode_rv | |
| Weaknesses | CWE-416 | |
| References |
|
Projects
Sign in to view the affected projects.
MITRE
Status: PUBLISHED
Assigner: CPANSec
Published:
Updated: 2026-11-14T11:54:10.777Z
Reserved: 2026-11-13T15:54:37.501Z
Link: CVE-2026-129115
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-11-14T12:17:44.120
Modified: 2026-11-14T12:17:44.120
Link: CVE-2026-129115
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses