Cloud security firm Wiz has revealed that it uncovered in-the-wild exploitation of a security flaw in a Linux utility known as Pandoc as a part of assaults designed to infiltrate Amazon Net Companies (AWS) Occasion Metadata Service (IMDS).
The vulnerability in query is CVE-2025-51591 (CVSS rating: 6.5), which refers to a case of Server-Aspect Request Forgery (SSRF) that permits attackers to compromise a goal system by injecting a specifically crafted HTML iframe ingredient.
The EC2 IMDS is a vital element of the AWS cloud atmosphere, providing details about working situations, in addition to non permanent, short-lived credentials if an identification and entry administration (IAM) function is related to the occasion. The occasion metadata is accessible to any utility working on an EC2 occasion by way of a link-local handle (169.254.169[.]254).
These credentials can then be used to securely work together with different AWS providers like S3, RDS, or DynamoDB, allowing functions to authenticate with out the necessity for storing credentials on the machine, thereby decreasing the danger of unintended publicity.
One of many frequent strategies that attackers can use to steal IAM credentials from IMDS is by way of SSRF flaws in internet functions. This primarily entails tricking the app working on an EC2 occasion to ship a request looking for IAM credentials from the IMDS service on its behalf.
“If the appliance can attain the IMDS endpoint and is prone to SSRF, the attacker can harvest non permanent credentials with no need any direct host entry (equivalent to RCE or path traversal),” Wiz researchers Hila Ramati and Gili Tikochinski stated.
An adversary seeking to goal AWS infrastructure can subsequently seek for SSRF vulnerabilities in internet functions working on EC2 situations and, when discovered, entry the occasion metadata and steal IAM credentials. This isn’t a theoretical risk.
Way back to early 2022, Google-owned Mandiant discovered {that a} risk actor it tracks as UNC2903 had attacked AWS environments by abusing credentials obtained utilizing IMDS since July 2021, exploiting an SSRF flaw (CVE-2021-21311, CVSS rating: 7.2) in Adminer, an open-source database administration device, to facilitate knowledge theft.
The problem, at its core, stems from the truth that IMDS, or extra particularly IMDSv1, is a request and response protocol, making it a lovely goal for dangerous actors who goal exploitable internet functions that additionally run IMDSv1.
In a report printed final month, Resecurity warned that when SSRF is exploited in opposition to cloud infrastructure like AWS, it could have “extreme and far-reaching” penalties, leading to cloud credential theft, community reconnaissance, and unauthorized entry to inner providers.
“Since SSRF originates from throughout the server, it could attain endpoints protected by perimeter firewalls. This successfully turns the susceptible utility right into a proxy, permitting the attacker to: Bypass IP whitelists [and] attain in any other case unreachable inner belongings,” it stated.
The newest findings from Wiz exhibit that assaults focusing on the IMDS service are persevering with to happen, with adversaries leveraging SSRF vulnerabilities in little-known functions like Pandoc to allow them.
“The vulnerability, tracked as CVE-2025-51591, stems from Pandoc rendering <iframe> tags in HTML paperwork,” Wiz researchers stated. “This could permit an attacker to craft an <iframe> that factors to the IMDS server, or different non-public sources.”
“The attacker submitted crafted HTML paperwork containing <iframe> components whose src attributes focused the AWS IMDS endpoint at 169.254.169[.]254. The target was to render and exfiltrate the content material of delicate paths, particularly /newest/meta-data/iam/data and /newest/meta-data/iam.”
Wiz stated the assault was finally unsuccessful due to the enforcement of IMDSv2, which is session-oriented and mitigates the SSRF assault by first requiring a consumer to get a token and use that token in all requests to the IMDS by way of a particular header (X-aws-ec2-metadata-token).
The corporate instructed The Hacker Information that it noticed in-the-wild exploitation makes an attempt “courting again to August and persevering with for a number of weeks,” including it additionally discovered continued efforts on the a part of unknown risk actors to abuse one other SSRF flaw in ClickHouse to unsuccessfully breach a goal’s Google Cloud Platform.
To mitigate the danger posed by CVE-2025-51591 in cloud environments, it is suggested to make use of the “-f html+raw_html” possibility or the “–sandbox” possibility to stop Pandoc from together with the contents of iframe components by the src attribute.
“[Pandoc maintainers] determined that rendering iframes is the meant habits and that the consumer is accountable to both sanitize the enter or use the sandbox flags when dealing with consumer inputs,” Wiz stated.
“Though Amazon recommends implementing the IMDSv2 with GuardDuty enhancements, EC2 situations created by Amazon clients that as an alternative use IMDSv1 could also be in danger when mixed with additionally working unpatched susceptible third get together software program,” Mandiant researchers warned on the time.
Organizations are beneficial to implement IMDSv2 throughout all EC2 situations and make sure that situations are assigned roles that comply with the precept of least privilege (PoLP) to comprise the blast radius within the occasion of an IMDS compromise.
