CVE-2026-15957

network-flow-monitor-agent-debuginfo: Package updates are available for Amazon Linux 2023 that fix the following vulnerabilities: CVE-2026-53587: libgit2...

CVE-2026-15957 is fixed in 4 products on 1 platform, first by ALAS2023-2026-3116, released September 28, 2026. It is not reported as exploited. Patch Radar priority: High.

High
CVSS
n/a
important
Exploitation
None reported
No vendor assessment
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0041
35th percentile

Package updates are available for Amazon Linux 2023 that fix the following vulnerabilities: CVE-2026-53587: libgit2 version 1.9.4 and below is vulnerable to a heap out-of-bounds read in set_data() in src/libgit2/transports/smart_pkt.c. The vulnerable code uses a fixed-size strncmp (smart_pkt.c:239) against the unvalidated capability buffer of a smart-protocol pkt-line. When the bytes following the pkt-line in the contiguous receive buffer happen to continue with "ct-format=", the comparison spuriously matches, advancing format_str past the pkt-line boundary. The following memchr(format_str, ' ', len - (format_str - line)) (smart_pkt.c:246) then underflows its size_t size argument to ~SIZE_MAX and walks the heap looking for a space byte. An unauthenticated remote attacker who controls (or man-in-the-middles) a Git server reached over HTTP/HTTPS/SSH/git:// can trigger this on the FIRST ref-pkt of the refs advertisement, before any capability negotiation has taken place. The OOB walk causes a process crash (SIGSEGV) when memchr enters an unmapped page, and -- on heap layouts where memchr finds a stray space byte before crashing -- can additionally drive the git_error_set("...'%.*s'", format_len, format_str) formatter to copy a large window of heap memory into the error string. CVE-2026-15957: Smithy-RS is a Rust code generation and runtime framework that generates HTTP clients and servers from Smithy interface definitions, powering the AWS SDK for Rust and custom service implementations. Uncontrolled recursion in the JSON, CBOR, and XML deserializer functions emitted by Amazon smithy-rs code generation could allow remote attackers to cause a denial of service (process abort via stack exhaustion) via a small request containing deeply nested data for a recursive model shape to a generated SDK or server. To mitigate this issue, users should upgrade to aws-sdk-rust release-2026-06-02 or later. Users building custom servers with smithy-rs codegen should regenerate from smithy-rs release-2026-06-01 or later.

Where it's fixed

ProductFixed inFixReleased
Linux
amazon-efs-utils · amzn 2023 3.1.3-1.amzn2023 ALAS2023-2026-3333 Nov 7, 2026
network-flow-monitor-agent · amzn 2023 1.1.8-1.amzn2023.0.1 ALAS2023-2026-3116 Sep 28, 2026
network-flow-monitor-agent-debuginfo · amzn 2023 1.1.8-1.amzn2023.0.1 ALAS2023-2026-3116 Sep 28, 2026
network-flow-monitor-agent-debugsource · amzn 2023 1.1.8-1.amzn2023.0.1 ALAS2023-2026-3116 Sep 28, 2026

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