CVSS2
Attack Vector
NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:N/AC:L/Au:N/C:P/I:P/A:P
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
Percentile
70.3%
This vulnerability is a memory safety Issue when using patch
or merge
on state
and assign the result back to state
.
In this case affected versions of Tremor and the tremor-script crate maintains references to memory that might have been freed already. And these memory regions can be accessed by retrieving the state
, e.g. send it over TCP or HTTP. This requires the Tremor server (or any other program using tremor-script) to execute a tremor-script script that uses the mentioned language construct.
If affects the following two tremor-script language constructs:
event
:let state = merge state of event end;
event
:let state = patch state of insert event.key => event.value end;
For constructs like this (it does not matter what it references in the expression to be merged or the patch operations) an optimization
was applied to manipulate the target value in-place, instead of cloning it.
Our Value
struct, which underpins all event data in tremor-script
, is representing strings as borrowed beef::Cow<'lifetime, str>
,
that reference the raw data Vec<u8>
the event is based upon. We keep this raw byte-array next to the Value
structure inside our Event
as a self-referential struct,
so we make sure that the structured Value
and its references are valid across its whole lifetime.
The optimization was considered safe as long as it was only possible to merge or patch event
data or static data.
When state
was introduced to tremor-script
(in version 0.7.3) a new possibility to keep Value
data around for longer than the lifetime of an event emerged.
If event
data is merged or patched into state
without cloning it first, it can still reference keys or values from
the previous event, which will now be invalid. This allows access to those already freed regions of memory and to get their content out over the wire.
The issue has been patched in https://crates.io/crates/tremor-script/0.11.6 and https://github.com/tremor-rs/tremor-runtime/releases/tag/v0.11.6 via commit 1a2efcd by removing the optimization
and always clone the target expression of a Merge or [Patch](https://www.tremor.rs/docs/tremor-script/index#patch.
If an upgrade is not possible, a possible workaround is to avoid the optimization
by introducing a temporary variable and not immediately reassigning to state
:
let tmp = merge state of event end;
let state = tmp
The actual fix is applied in this PR: https://github.com/tremor-rs/tremor-runtime/pull/1217
If you have any questions or comments about this advisory:
Vendor | Product | Version | CPE |
---|---|---|---|
linuxfoundation | tremor-script | * | cpe:2.3:a:linuxfoundation:tremor-script:*:*:*:*:*:rust:*:* |
github.com/advisories/GHSA-mc22-5q92-8v85
github.com/tremor-rs/tremor-runtime/commit/1a2efcdbe68e5e7fd0a05836ac32d2cde78a0b2e
github.com/tremor-rs/tremor-runtime/pull/1217
github.com/tremor-rs/tremor-runtime/releases/tag/v0.11.6
github.com/tremor-rs/tremor-runtime/security/advisories/GHSA-mc22-5q92-8v85
nvd.nist.gov/vuln/detail/CVE-2021-39228
CVSS2
Attack Vector
NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:N/AC:L/Au:N/C:P/I:P/A:P
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
Percentile
70.3%